Nanostructural characterization of CrN and CO thin films on silicon substrate, modified by ion bombardment
Thin film structures own significantly different properties than the bulk material and consequently they found applications in various fields of modern nanotechnology. In the past few decades, special attention was paid to research in the field of ion beams modification of thin films. Among the tech...
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| description | Thin film structures own significantly different properties than the bulk
material and consequently they found applications in various fields of modern
nanotechnology. In the past few decades, special attention was paid to
research in the field of ion beams modification of thin films. Among the
techniques ion implantation is particularly emphasized, as a method that
allows the incorporation of impurity atoms in the material with the
possibility of precise control of process parameters. As non-equilibrium
technique (not controlled by diffusion laws), ion implantation enables
production of a new materials, that can not be produced with other
conventional methods. The main objective of this research was to gain new
fundamental knowledge in the field of modification of thin film/Si systems
induced by ion irradiation. The present work consists of two parts. In the
first part of the experiment the changes induced by ion implantation inside
of the thin layer were examined – effects of different ionic species on the
microstructure, optical and electrical properties of chromium nitride (CrN)
were investigated. The second part of the experiment refers to the
examination of changes at the thin film/substrate interface due to ion
implantation – the influence of ion bombardment on the ion beam mixing of
Co/Si system was investigated as well as formation of cobalt-silicides during
the process of ion irradiation and./.or annealing of the samples. Rutherford
backscattering spectrometry (RBS) was used to obtain concentration depth
profiles of elements and to determine the stoichiometry of the layers.
Structural and phase analyses of the systems were performed by X-ray
diffraction (XRD), transmission electron microscopy combined with selected
area diffraction (TEM/ SAD) and high-resolution electron microscopy analysis
together with fast Fourier transformations (HRTEM/FFT). Optical properties of
modified CrN layers were determined using infrared spectroscopy (IR) and
electrical resistivity was measured using four point probe method. CrN thin
films (thickness of ~280 nm) were deposited by reactive sputtering on
crystalline silicon substrates and then implanted with 200 keV Ar+ and 80 keV
V+ ions. In the case of Ar+ ions the samples were implanted in the range of
5×1015–20×1015 ions/cm2, while V+ ions were implanted to the fluence of
1×1017 and 2×1017 ions/cm2. The energies were chosen in such a way that all
ions are stopped inside the layer, to avoid any atomic mixing and pos |
| format | Dissertation |
| fullrecord | <record><control><sourceid>europeana_1GC</sourceid><recordid>TN_cdi_europeana_collections_9200447_BibliographicResource_3000095542567</recordid><sourceformat>XML</sourceformat><sourcesystem>PC</sourcesystem><sourcerecordid>9200447_BibliographicResource_3000095542567</sourcerecordid><originalsourceid>FETCH-europeana_collections_9200447_BibliographicResource_30000955425673</originalsourceid><addsrcrecordid>eNqtjTEKwkAQRdNYiHqHOYBC0ESxNShWCmIfZjcTM7LZkdndQk9vAh7B37zi89-fZs8LeglRk41J0YHtUNFGUv5gZPEgLVR6AfQNVFeIHXto2fUBhi6wYzsymUGBkZbQS8MtUwPmDePcSG9Qm558nGeTFl2gxY-z7Hw63qvzipLKi9BjbcU5suNvqPfrPC-KXX1g41geiq-O7Y2CJLVUb_Ih-7Is1uV2t_mj6gunIl0a</addsrcrecordid><sourcetype>Aggregation Database</sourcetype><iscdi>true</iscdi><recordtype>dissertation</recordtype></control><display><type>dissertation</type><title>Nanostructural characterization of CrN and CO thin films on silicon substrate, modified by ion bombardment</title><source>Europeana Collections</source><creator>Novaković Mirjana</creator><creatorcontrib>Novaković Mirjana ; Miljanić Šćepan ; Bibić Nataša</creatorcontrib><description>Thin film structures own significantly different properties than the bulk
material and consequently they found applications in various fields of modern
nanotechnology. In the past few decades, special attention was paid to
research in the field of ion beams modification of thin films. Among the
techniques ion implantation is particularly emphasized, as a method that
allows the incorporation of impurity atoms in the material with the
possibility of precise control of process parameters. As non-equilibrium
technique (not controlled by diffusion laws), ion implantation enables
production of a new materials, that can not be produced with other
conventional methods. The main objective of this research was to gain new
fundamental knowledge in the field of modification of thin film/Si systems
induced by ion irradiation. The present work consists of two parts. In the
first part of the experiment the changes induced by ion implantation inside
of the thin layer were examined – effects of different ionic species on the
microstructure, optical and electrical properties of chromium nitride (CrN)
were investigated. The second part of the experiment refers to the
examination of changes at the thin film/substrate interface due to ion
implantation – the influence of ion bombardment on the ion beam mixing of
Co/Si system was investigated as well as formation of cobalt-silicides during
the process of ion irradiation and./.or annealing of the samples. Rutherford
backscattering spectrometry (RBS) was used to obtain concentration depth
profiles of elements and to determine the stoichiometry of the layers.
Structural and phase analyses of the systems were performed by X-ray
diffraction (XRD), transmission electron microscopy combined with selected
area diffraction (TEM/ SAD) and high-resolution electron microscopy analysis
together with fast Fourier transformations (HRTEM/FFT). Optical properties of
modified CrN layers were determined using infrared spectroscopy (IR) and
electrical resistivity was measured using four point probe method. CrN thin
films (thickness of ~280 nm) were deposited by reactive sputtering on
crystalline silicon substrates and then implanted with 200 keV Ar+ and 80 keV
V+ ions. In the case of Ar+ ions the samples were implanted in the range of
5×1015–20×1015 ions/cm2, while V+ ions were implanted to the fluence of
1×1017 and 2×1017 ions/cm2. The energies were chosen in such a way that all
ions are stopped inside the layer, to avoid any atomic mixing and possible
reactions at the thin film./.substrate interface. It turned out that
different ionic species produces different effects in the layer, which is
manifested in both the microstructural changes, as well as changes in optical
and electrical properties of this material. After irradiation with Ar+ ions
there are no significant changes in the composition of the layer. However,
the changes were observed in the microstructure of the samples. In the
implantation region the initial columnar structure of the layer firstly
becomes broken and with increasing of ion fluence completely destroyed. The
accumulation of defects within this area produces damage and the internal
stresses in the layer, which affects the size of crystalline grains and the
values of the CrN lattice constant. In contrast to the implantation of inert
argon which produces only ion irradiation induced damage, the presence of
vanadium, as the second transition metal, leads to the generation of chemical
effects in the layer. It was observed that in the region of the layer with
the highest concentration of implanted vanadium Cr0,9375 V0,0625N compound
was formed. Due to the formation of a new metallic phase, as deposited CrN
layer with metal/semiconductor properties shows a purely metallic character
after V+ implantation. Co(50nm)/Si bilayers were prepared in high vacuum
conditions, using ion beam assisted deposition technique. Two types of
silicon substrates were used: crystalline (100) wafers and Si wafers
pre-amorphized by low-energy Ar+ ion bombardment. After deposition the layers
were implanted with 400 keV Xe+ ions to the fluence of 2×1015, 4×1015,
6×1015, 8×1015, 10×1015, 15×1015, 20×1015 and 30×1015 ions/cm2. The energy
was chosen so that the effects of ion implantation are most pronounced at the
thin film (Co)./.substrate (Si) interface. Then, as deposited and selected
implanted samples (20×1015 Xe/cm2) were annealed for 2.h in the vacuum
furnace at 200, 300, 400, 500, 600 and 700ºC. The values of atomic mixing
rates showed that the structure of the substrate has a strong influence on
the process of atomic transport induced by ion bombardment. Namely, in the
case of pre-amorphized substrate the mixing rate of Co and Si atoms at the
Co/Si interface is almost for an order of magnitude lower in comparation with
crystalline Si. It is assumed that this is the result of the formation of
large amount of defects, created near the surface of Si substrate during the
Ar+ ions bombardment, which presents a barrier for movement of atoms from one
to the other side of the interface. Low mobility of these defects prevents
also the thermally activated diffusion, so even at the highest annealing
temperature the formation of silicides was not observed. For the irradiated
samples, independently on whether it is crystalline or pre-amorphized
substrate, it is observed similar behavior: up to annealing temperatures of
400ºC poorly pronounced diffusion comes from the effects induced by ion
irradiation, and at temperatures of 500–700ºC thermal mixing becomes dominant
process and conditions for the compound formation were fulfilled. At the
temperature of 500ºC dominant phase is CoSi, and at temperatures ≥600ºC a
pure phase CoSi2 was formed.
Zbog činjenice da posjeduju svojstva koja se znatno razlikuju od komadnog
materijala, tankoslojne strukture su našle primjenu u raznim oblastima
savremenih nanotehnologija. U posljednjih nekoliko decenija posebna pažnja je
posvećena istraživanjima na polju modifikacije tankih slojeva korišćenjem
jonskih snopova. Medu tehnikama se posebno istakla jonska implantacija, kao
metoda koja omogućuje ugrađivanje atoma nečistoća u materijal u strogo
kontrolisanim uslovima. Kao neravnotežna tehnika (nije kontrolisana zakonima
difuzije), jonska implantacija omogućuje dobijanje novih materijala, koji se
drugim postupcima ne mogu formirati. Osnovni cilj ovog istraživanja je
sticanje novih fundamentalnih znanja u oblasti modifikacije sistema tanak
sloj/Si primjenom jonskog zračenja. Predstavljeni rad se sastoji iz dva
dijela. U prvom dijelu eksperimenta su posmatrane promjene koje jonska
implantacija indukuje unutar tankog sloja – ispitivan je efekat različitih
jonskih vrsta na mikrostrukturu, optička i električna svojstva hrom-nitrida
(CrN). Drugi dio eksperimenta se odnosi na ispitivanje promjena koje uslijed
jonske implantacije nastaju na granici tanak sloj/podloga – proučavan je
uticaj jonskog bombardovanja na proces atomskog transporta kod Co/Si sistema
i mogućnost formiranja kobalt-silicida u toku procesa jonskog zračenja i/ili
odgrijavanja uzoraka. Spektrometrija Rutherford-ovim povratnim rasijanjem
(RBS) je iskorišćena za dobijanje dubinskih koncentracionih profila elemenata
i određivanje stehiometrije slojeva. Za strukturnu analizu i identifikaciju
prisutnih faza u uzorcima korišćena je difrakcija X-zračenja (XRD),
transmisiona elektronska mikroskopija u kombinaciji sa elektronskom
difrakcijom na odabranoj površini (TEM/SAD) i visoko-rezoluciona elektronska
mikroskopija uz analizu pomoću Fourier-ove transformacije (HRTEM/FFT).
Optička svojstva modifikovanih CrN slojeva su određena korišćenjem
infracrvene spektrofotometrije (IR), a električna otpornost je mjerena
metodom ”četiri tačke”. Tanki slojevi CrN (debljine ~280 nm) su deponovani
metodom reaktivnog jonskog rasprašivanja na kristalnim silicijumskim
pločicama, a zatim su implantirani sa 200 keV Ar+ i 80 keV V+ jonima. U
slučaju Ar+ jona uzorci su implantirani u opsegu od 5×1015–20×1015 jona/cm2,
dok su joni V+ implantirani do doze 1×1017 i 2×1017 jona/cm2. Energije su
odabrane tako da se svi joni zaustave u sloju, da bi se izbjeglo atomsko
miješanje i moguće reakcije na granici sloj/podloga. Pokazalo se da različite
jonske vrste proizvode drugačije efekte u sloju, što se manifestovalo kako u
mikrostrukturnim promjenama, tako i u promjenama optičkih i električnih
svojstava ovog materijala. Nakon ozračivanja sa jonima Ar+ ne dolazi do
značajnih promjena u sastavu sloja. Međutim, uočene su promjene u
mikrostrukturi uzoraka. U zoni implantacije prvo dolazi do narušavanja, a sa
povećanjem doze i do potpunog uništenja prvobitne stubičaste strukture sloja.
Nakupljanje defekata unutar ove oblasti proizvodi oštećenja i unutrašnja
naprezanja u sloju, što utiče na veličinu kristalnih zrna i na vrijednost
konstante CrN rešetke. Za razliku od implantacije inertnog argona gdje dolazi
samo do pojave jonskim zračenjem indukovanog oštećenja, prisustvo vanadijuma,
kao drugog prelaznog metala, dovodi do pojave hemijskih efekata u sloju.
Uočeno je da u zoni sloja sa najvećom koncentracijom implantiranog vanadijuma
dolazi do formiranja Cr0,9375 V0,0625.N jedinjenja. Formiranje nove metalne
faze ima za posljedicu da deponovani CrN sloj sa metalno/poluprovodničkim
svojstvima, nakon V+ implantacije pokazuje izraziti metalni karakter.
Dvoslojni sistemi Co(50nm)/Si su pripremljeni u uslovima visokog vakuuma,
korišćenjem metode deponovanja potpomognutog jonskim snopom. Korišćene su
dvije vrste silicijumskih podloga: kristalne pločice orijentacije (100) i
podloge sa površinom amorfizovanom bombardovanjem sa niskoenergetskim Ar+
jonima. Nakon deponovanja slojevi su implantirani sa 400 keV Xe+ jonima do
doze 2×1015, 4×1015, 6×1015, 8×1015, 10×1015, 15×1015, 20×1015 i 30×1015
jona/cm2. Energija je odabrana tako da efekti jonske implantacije budu
najizraženiji na granici tanak sloj (Co)/podloga (Si). Deponovani i odabrani
implantirani slojevi (20×1015 Xe/cm2) su za</description><language>srp</language><publisher>University of Belgrade, Faculty of Physical Chemistry</publisher><subject>CrN thin films ; IBM technique ; IBM tehnika ; ion implantation ; IR spectroscopy ; IR spektrofotometrija ; jonska implantacija ; RBS ; silicides ; silicidi ; tanki slojevi CrN ; TEM analiza ; TEM analysis ; XRD</subject><creationdate>2012</creationdate><oa>free_for_read</oa><woscitedreferencessubscribed>false</woscitedreferencessubscribed></display><links><openurl>$$Topenurl_article</openurl><openurlfulltext>$$Topenurlfull_article</openurlfulltext><thumbnail>$$Tsyndetics_thumb_exl</thumbnail><linktohtml>$$Uhttps://data.europeana.eu/item/9200447/BibliographicResource_3000095542567$$EHTML$$P50$$Geuropeana$$Hfree_for_read</linktohtml><link.rule.ids>311,776,38494,75918</link.rule.ids><linktorsrc>$$Uhttps://data.europeana.eu/item/9200447/BibliographicResource_3000095542567$$EView_record_in_Europeana$$FView_record_in_$$GEuropeana$$Hfree_for_read</linktorsrc></links><search><creatorcontrib>Novaković Mirjana</creatorcontrib><title>Nanostructural characterization of CrN and CO thin films on silicon substrate, modified by ion bombardment</title><description>Thin film structures own significantly different properties than the bulk
material and consequently they found applications in various fields of modern
nanotechnology. In the past few decades, special attention was paid to
research in the field of ion beams modification of thin films. Among the
techniques ion implantation is particularly emphasized, as a method that
allows the incorporation of impurity atoms in the material with the
possibility of precise control of process parameters. As non-equilibrium
technique (not controlled by diffusion laws), ion implantation enables
production of a new materials, that can not be produced with other
conventional methods. The main objective of this research was to gain new
fundamental knowledge in the field of modification of thin film/Si systems
induced by ion irradiation. The present work consists of two parts. In the
first part of the experiment the changes induced by ion implantation inside
of the thin layer were examined – effects of different ionic species on the
microstructure, optical and electrical properties of chromium nitride (CrN)
were investigated. The second part of the experiment refers to the
examination of changes at the thin film/substrate interface due to ion
implantation – the influence of ion bombardment on the ion beam mixing of
Co/Si system was investigated as well as formation of cobalt-silicides during
the process of ion irradiation and./.or annealing of the samples. Rutherford
backscattering spectrometry (RBS) was used to obtain concentration depth
profiles of elements and to determine the stoichiometry of the layers.
Structural and phase analyses of the systems were performed by X-ray
diffraction (XRD), transmission electron microscopy combined with selected
area diffraction (TEM/ SAD) and high-resolution electron microscopy analysis
together with fast Fourier transformations (HRTEM/FFT). Optical properties of
modified CrN layers were determined using infrared spectroscopy (IR) and
electrical resistivity was measured using four point probe method. CrN thin
films (thickness of ~280 nm) were deposited by reactive sputtering on
crystalline silicon substrates and then implanted with 200 keV Ar+ and 80 keV
V+ ions. In the case of Ar+ ions the samples were implanted in the range of
5×1015–20×1015 ions/cm2, while V+ ions were implanted to the fluence of
1×1017 and 2×1017 ions/cm2. The energies were chosen in such a way that all
ions are stopped inside the layer, to avoid any atomic mixing and possible
reactions at the thin film./.substrate interface. It turned out that
different ionic species produces different effects in the layer, which is
manifested in both the microstructural changes, as well as changes in optical
and electrical properties of this material. After irradiation with Ar+ ions
there are no significant changes in the composition of the layer. However,
the changes were observed in the microstructure of the samples. In the
implantation region the initial columnar structure of the layer firstly
becomes broken and with increasing of ion fluence completely destroyed. The
accumulation of defects within this area produces damage and the internal
stresses in the layer, which affects the size of crystalline grains and the
values of the CrN lattice constant. In contrast to the implantation of inert
argon which produces only ion irradiation induced damage, the presence of
vanadium, as the second transition metal, leads to the generation of chemical
effects in the layer. It was observed that in the region of the layer with
the highest concentration of implanted vanadium Cr0,9375 V0,0625N compound
was formed. Due to the formation of a new metallic phase, as deposited CrN
layer with metal/semiconductor properties shows a purely metallic character
after V+ implantation. Co(50nm)/Si bilayers were prepared in high vacuum
conditions, using ion beam assisted deposition technique. Two types of
silicon substrates were used: crystalline (100) wafers and Si wafers
pre-amorphized by low-energy Ar+ ion bombardment. After deposition the layers
were implanted with 400 keV Xe+ ions to the fluence of 2×1015, 4×1015,
6×1015, 8×1015, 10×1015, 15×1015, 20×1015 and 30×1015 ions/cm2. The energy
was chosen so that the effects of ion implantation are most pronounced at the
thin film (Co)./.substrate (Si) interface. Then, as deposited and selected
implanted samples (20×1015 Xe/cm2) were annealed for 2.h in the vacuum
furnace at 200, 300, 400, 500, 600 and 700ºC. The values of atomic mixing
rates showed that the structure of the substrate has a strong influence on
the process of atomic transport induced by ion bombardment. Namely, in the
case of pre-amorphized substrate the mixing rate of Co and Si atoms at the
Co/Si interface is almost for an order of magnitude lower in comparation with
crystalline Si. It is assumed that this is the result of the formation of
large amount of defects, created near the surface of Si substrate during the
Ar+ ions bombardment, which presents a barrier for movement of atoms from one
to the other side of the interface. Low mobility of these defects prevents
also the thermally activated diffusion, so even at the highest annealing
temperature the formation of silicides was not observed. For the irradiated
samples, independently on whether it is crystalline or pre-amorphized
substrate, it is observed similar behavior: up to annealing temperatures of
400ºC poorly pronounced diffusion comes from the effects induced by ion
irradiation, and at temperatures of 500–700ºC thermal mixing becomes dominant
process and conditions for the compound formation were fulfilled. At the
temperature of 500ºC dominant phase is CoSi, and at temperatures ≥600ºC a
pure phase CoSi2 was formed.
Zbog činjenice da posjeduju svojstva koja se znatno razlikuju od komadnog
materijala, tankoslojne strukture su našle primjenu u raznim oblastima
savremenih nanotehnologija. U posljednjih nekoliko decenija posebna pažnja je
posvećena istraživanjima na polju modifikacije tankih slojeva korišćenjem
jonskih snopova. Medu tehnikama se posebno istakla jonska implantacija, kao
metoda koja omogućuje ugrađivanje atoma nečistoća u materijal u strogo
kontrolisanim uslovima. Kao neravnotežna tehnika (nije kontrolisana zakonima
difuzije), jonska implantacija omogućuje dobijanje novih materijala, koji se
drugim postupcima ne mogu formirati. Osnovni cilj ovog istraživanja je
sticanje novih fundamentalnih znanja u oblasti modifikacije sistema tanak
sloj/Si primjenom jonskog zračenja. Predstavljeni rad se sastoji iz dva
dijela. U prvom dijelu eksperimenta su posmatrane promjene koje jonska
implantacija indukuje unutar tankog sloja – ispitivan je efekat različitih
jonskih vrsta na mikrostrukturu, optička i električna svojstva hrom-nitrida
(CrN). Drugi dio eksperimenta se odnosi na ispitivanje promjena koje uslijed
jonske implantacije nastaju na granici tanak sloj/podloga – proučavan je
uticaj jonskog bombardovanja na proces atomskog transporta kod Co/Si sistema
i mogućnost formiranja kobalt-silicida u toku procesa jonskog zračenja i/ili
odgrijavanja uzoraka. Spektrometrija Rutherford-ovim povratnim rasijanjem
(RBS) je iskorišćena za dobijanje dubinskih koncentracionih profila elemenata
i određivanje stehiometrije slojeva. Za strukturnu analizu i identifikaciju
prisutnih faza u uzorcima korišćena je difrakcija X-zračenja (XRD),
transmisiona elektronska mikroskopija u kombinaciji sa elektronskom
difrakcijom na odabranoj površini (TEM/SAD) i visoko-rezoluciona elektronska
mikroskopija uz analizu pomoću Fourier-ove transformacije (HRTEM/FFT).
Optička svojstva modifikovanih CrN slojeva su određena korišćenjem
infracrvene spektrofotometrije (IR), a električna otpornost je mjerena
metodom ”četiri tačke”. Tanki slojevi CrN (debljine ~280 nm) su deponovani
metodom reaktivnog jonskog rasprašivanja na kristalnim silicijumskim
pločicama, a zatim su implantirani sa 200 keV Ar+ i 80 keV V+ jonima. U
slučaju Ar+ jona uzorci su implantirani u opsegu od 5×1015–20×1015 jona/cm2,
dok su joni V+ implantirani do doze 1×1017 i 2×1017 jona/cm2. Energije su
odabrane tako da se svi joni zaustave u sloju, da bi se izbjeglo atomsko
miješanje i moguće reakcije na granici sloj/podloga. Pokazalo se da različite
jonske vrste proizvode drugačije efekte u sloju, što se manifestovalo kako u
mikrostrukturnim promjenama, tako i u promjenama optičkih i električnih
svojstava ovog materijala. Nakon ozračivanja sa jonima Ar+ ne dolazi do
značajnih promjena u sastavu sloja. Međutim, uočene su promjene u
mikrostrukturi uzoraka. U zoni implantacije prvo dolazi do narušavanja, a sa
povećanjem doze i do potpunog uništenja prvobitne stubičaste strukture sloja.
Nakupljanje defekata unutar ove oblasti proizvodi oštećenja i unutrašnja
naprezanja u sloju, što utiče na veličinu kristalnih zrna i na vrijednost
konstante CrN rešetke. Za razliku od implantacije inertnog argona gdje dolazi
samo do pojave jonskim zračenjem indukovanog oštećenja, prisustvo vanadijuma,
kao drugog prelaznog metala, dovodi do pojave hemijskih efekata u sloju.
Uočeno je da u zoni sloja sa najvećom koncentracijom implantiranog vanadijuma
dolazi do formiranja Cr0,9375 V0,0625.N jedinjenja. Formiranje nove metalne
faze ima za posljedicu da deponovani CrN sloj sa metalno/poluprovodničkim
svojstvima, nakon V+ implantacije pokazuje izraziti metalni karakter.
Dvoslojni sistemi Co(50nm)/Si su pripremljeni u uslovima visokog vakuuma,
korišćenjem metode deponovanja potpomognutog jonskim snopom. Korišćene su
dvije vrste silicijumskih podloga: kristalne pločice orijentacije (100) i
podloge sa površinom amorfizovanom bombardovanjem sa niskoenergetskim Ar+
jonima. Nakon deponovanja slojevi su implantirani sa 400 keV Xe+ jonima do
doze 2×1015, 4×1015, 6×1015, 8×1015, 10×1015, 15×1015, 20×1015 i 30×1015
jona/cm2. Energija je odabrana tako da efekti jonske implantacije budu
najizraženiji na granici tanak sloj (Co)/podloga (Si). Deponovani i odabrani
implantirani slojevi (20×1015 Xe/cm2) su za</description><subject>CrN thin films</subject><subject>IBM technique</subject><subject>IBM tehnika</subject><subject>ion implantation</subject><subject>IR spectroscopy</subject><subject>IR spektrofotometrija</subject><subject>jonska implantacija</subject><subject>RBS</subject><subject>silicides</subject><subject>silicidi</subject><subject>tanki slojevi CrN</subject><subject>TEM analiza</subject><subject>TEM analysis</subject><subject>XRD</subject><fulltext>true</fulltext><rsrctype>dissertation</rsrctype><creationdate>2012</creationdate><recordtype>dissertation</recordtype><sourceid>1GC</sourceid><recordid>eNqtjTEKwkAQRdNYiHqHOYBC0ESxNShWCmIfZjcTM7LZkdndQk9vAh7B37zi89-fZs8LeglRk41J0YHtUNFGUv5gZPEgLVR6AfQNVFeIHXto2fUBhi6wYzsymUGBkZbQS8MtUwPmDePcSG9Qm558nGeTFl2gxY-z7Hw63qvzipLKi9BjbcU5suNvqPfrPC-KXX1g41geiq-O7Y2CJLVUb_Ih-7Is1uV2t_mj6gunIl0a</recordid><startdate>20121221</startdate><enddate>20121221</enddate><creator>Novaković Mirjana</creator><general>University of Belgrade, Faculty of Physical Chemistry</general><scope>1GC</scope></search><sort><creationdate>20121221</creationdate><title>Nanostructural characterization of CrN and CO thin films on silicon substrate, modified by ion bombardment</title><author>Novaković Mirjana</author></sort><facets><frbrtype>5</frbrtype><frbrgroupid>cdi_FETCH-europeana_collections_9200447_BibliographicResource_30000955425673</frbrgroupid><rsrctype>dissertations</rsrctype><prefilter>dissertations</prefilter><language>srp</language><creationdate>2012</creationdate><topic>CrN thin films</topic><topic>IBM technique</topic><topic>IBM tehnika</topic><topic>ion implantation</topic><topic>IR spectroscopy</topic><topic>IR spektrofotometrija</topic><topic>jonska implantacija</topic><topic>RBS</topic><topic>silicides</topic><topic>silicidi</topic><topic>tanki slojevi CrN</topic><topic>TEM analiza</topic><topic>TEM analysis</topic><topic>XRD</topic><toplevel>online_resources</toplevel><creatorcontrib>Novaković Mirjana</creatorcontrib><collection>Europeana Collections</collection></facets><delivery><delcategory>Remote Search Resource</delcategory><fulltext>fulltext_linktorsrc</fulltext></delivery><addata><au>Novaković Mirjana</au><format>dissertation</format><genre>dissertation</genre><ristype>THES</ristype><Advisor>Miljanić Šćepan</Advisor><Advisor>Bibić Nataša</Advisor><btitle>Nanostructural characterization of CrN and CO thin films on silicon substrate, modified by ion bombardment</btitle><date>2012-12-21</date><risdate>2012</risdate><abstract>Thin film structures own significantly different properties than the bulk
material and consequently they found applications in various fields of modern
nanotechnology. In the past few decades, special attention was paid to
research in the field of ion beams modification of thin films. Among the
techniques ion implantation is particularly emphasized, as a method that
allows the incorporation of impurity atoms in the material with the
possibility of precise control of process parameters. As non-equilibrium
technique (not controlled by diffusion laws), ion implantation enables
production of a new materials, that can not be produced with other
conventional methods. The main objective of this research was to gain new
fundamental knowledge in the field of modification of thin film/Si systems
induced by ion irradiation. The present work consists of two parts. In the
first part of the experiment the changes induced by ion implantation inside
of the thin layer were examined – effects of different ionic species on the
microstructure, optical and electrical properties of chromium nitride (CrN)
were investigated. The second part of the experiment refers to the
examination of changes at the thin film/substrate interface due to ion
implantation – the influence of ion bombardment on the ion beam mixing of
Co/Si system was investigated as well as formation of cobalt-silicides during
the process of ion irradiation and./.or annealing of the samples. Rutherford
backscattering spectrometry (RBS) was used to obtain concentration depth
profiles of elements and to determine the stoichiometry of the layers.
Structural and phase analyses of the systems were performed by X-ray
diffraction (XRD), transmission electron microscopy combined with selected
area diffraction (TEM/ SAD) and high-resolution electron microscopy analysis
together with fast Fourier transformations (HRTEM/FFT). Optical properties of
modified CrN layers were determined using infrared spectroscopy (IR) and
electrical resistivity was measured using four point probe method. CrN thin
films (thickness of ~280 nm) were deposited by reactive sputtering on
crystalline silicon substrates and then implanted with 200 keV Ar+ and 80 keV
V+ ions. In the case of Ar+ ions the samples were implanted in the range of
5×1015–20×1015 ions/cm2, while V+ ions were implanted to the fluence of
1×1017 and 2×1017 ions/cm2. The energies were chosen in such a way that all
ions are stopped inside the layer, to avoid any atomic mixing and possible
reactions at the thin film./.substrate interface. It turned out that
different ionic species produces different effects in the layer, which is
manifested in both the microstructural changes, as well as changes in optical
and electrical properties of this material. After irradiation with Ar+ ions
there are no significant changes in the composition of the layer. However,
the changes were observed in the microstructure of the samples. In the
implantation region the initial columnar structure of the layer firstly
becomes broken and with increasing of ion fluence completely destroyed. The
accumulation of defects within this area produces damage and the internal
stresses in the layer, which affects the size of crystalline grains and the
values of the CrN lattice constant. In contrast to the implantation of inert
argon which produces only ion irradiation induced damage, the presence of
vanadium, as the second transition metal, leads to the generation of chemical
effects in the layer. It was observed that in the region of the layer with
the highest concentration of implanted vanadium Cr0,9375 V0,0625N compound
was formed. Due to the formation of a new metallic phase, as deposited CrN
layer with metal/semiconductor properties shows a purely metallic character
after V+ implantation. Co(50nm)/Si bilayers were prepared in high vacuum
conditions, using ion beam assisted deposition technique. Two types of
silicon substrates were used: crystalline (100) wafers and Si wafers
pre-amorphized by low-energy Ar+ ion bombardment. After deposition the layers
were implanted with 400 keV Xe+ ions to the fluence of 2×1015, 4×1015,
6×1015, 8×1015, 10×1015, 15×1015, 20×1015 and 30×1015 ions/cm2. The energy
was chosen so that the effects of ion implantation are most pronounced at the
thin film (Co)./.substrate (Si) interface. Then, as deposited and selected
implanted samples (20×1015 Xe/cm2) were annealed for 2.h in the vacuum
furnace at 200, 300, 400, 500, 600 and 700ºC. The values of atomic mixing
rates showed that the structure of the substrate has a strong influence on
the process of atomic transport induced by ion bombardment. Namely, in the
case of pre-amorphized substrate the mixing rate of Co and Si atoms at the
Co/Si interface is almost for an order of magnitude lower in comparation with
crystalline Si. It is assumed that this is the result of the formation of
large amount of defects, created near the surface of Si substrate during the
Ar+ ions bombardment, which presents a barrier for movement of atoms from one
to the other side of the interface. Low mobility of these defects prevents
also the thermally activated diffusion, so even at the highest annealing
temperature the formation of silicides was not observed. For the irradiated
samples, independently on whether it is crystalline or pre-amorphized
substrate, it is observed similar behavior: up to annealing temperatures of
400ºC poorly pronounced diffusion comes from the effects induced by ion
irradiation, and at temperatures of 500–700ºC thermal mixing becomes dominant
process and conditions for the compound formation were fulfilled. At the
temperature of 500ºC dominant phase is CoSi, and at temperatures ≥600ºC a
pure phase CoSi2 was formed.
Zbog činjenice da posjeduju svojstva koja se znatno razlikuju od komadnog
materijala, tankoslojne strukture su našle primjenu u raznim oblastima
savremenih nanotehnologija. U posljednjih nekoliko decenija posebna pažnja je
posvećena istraživanjima na polju modifikacije tankih slojeva korišćenjem
jonskih snopova. Medu tehnikama se posebno istakla jonska implantacija, kao
metoda koja omogućuje ugrađivanje atoma nečistoća u materijal u strogo
kontrolisanim uslovima. Kao neravnotežna tehnika (nije kontrolisana zakonima
difuzije), jonska implantacija omogućuje dobijanje novih materijala, koji se
drugim postupcima ne mogu formirati. Osnovni cilj ovog istraživanja je
sticanje novih fundamentalnih znanja u oblasti modifikacije sistema tanak
sloj/Si primjenom jonskog zračenja. Predstavljeni rad se sastoji iz dva
dijela. U prvom dijelu eksperimenta su posmatrane promjene koje jonska
implantacija indukuje unutar tankog sloja – ispitivan je efekat različitih
jonskih vrsta na mikrostrukturu, optička i električna svojstva hrom-nitrida
(CrN). Drugi dio eksperimenta se odnosi na ispitivanje promjena koje uslijed
jonske implantacije nastaju na granici tanak sloj/podloga – proučavan je
uticaj jonskog bombardovanja na proces atomskog transporta kod Co/Si sistema
i mogućnost formiranja kobalt-silicida u toku procesa jonskog zračenja i/ili
odgrijavanja uzoraka. Spektrometrija Rutherford-ovim povratnim rasijanjem
(RBS) je iskorišćena za dobijanje dubinskih koncentracionih profila elemenata
i određivanje stehiometrije slojeva. Za strukturnu analizu i identifikaciju
prisutnih faza u uzorcima korišćena je difrakcija X-zračenja (XRD),
transmisiona elektronska mikroskopija u kombinaciji sa elektronskom
difrakcijom na odabranoj površini (TEM/SAD) i visoko-rezoluciona elektronska
mikroskopija uz analizu pomoću Fourier-ove transformacije (HRTEM/FFT).
Optička svojstva modifikovanih CrN slojeva su određena korišćenjem
infracrvene spektrofotometrije (IR), a električna otpornost je mjerena
metodom ”četiri tačke”. Tanki slojevi CrN (debljine ~280 nm) su deponovani
metodom reaktivnog jonskog rasprašivanja na kristalnim silicijumskim
pločicama, a zatim su implantirani sa 200 keV Ar+ i 80 keV V+ jonima. U
slučaju Ar+ jona uzorci su implantirani u opsegu od 5×1015–20×1015 jona/cm2,
dok su joni V+ implantirani do doze 1×1017 i 2×1017 jona/cm2. Energije su
odabrane tako da se svi joni zaustave u sloju, da bi se izbjeglo atomsko
miješanje i moguće reakcije na granici sloj/podloga. Pokazalo se da različite
jonske vrste proizvode drugačije efekte u sloju, što se manifestovalo kako u
mikrostrukturnim promjenama, tako i u promjenama optičkih i električnih
svojstava ovog materijala. Nakon ozračivanja sa jonima Ar+ ne dolazi do
značajnih promjena u sastavu sloja. Međutim, uočene su promjene u
mikrostrukturi uzoraka. U zoni implantacije prvo dolazi do narušavanja, a sa
povećanjem doze i do potpunog uništenja prvobitne stubičaste strukture sloja.
Nakupljanje defekata unutar ove oblasti proizvodi oštećenja i unutrašnja
naprezanja u sloju, što utiče na veličinu kristalnih zrna i na vrijednost
konstante CrN rešetke. Za razliku od implantacije inertnog argona gdje dolazi
samo do pojave jonskim zračenjem indukovanog oštećenja, prisustvo vanadijuma,
kao drugog prelaznog metala, dovodi do pojave hemijskih efekata u sloju.
Uočeno je da u zoni sloja sa najvećom koncentracijom implantiranog vanadijuma
dolazi do formiranja Cr0,9375 V0,0625.N jedinjenja. Formiranje nove metalne
faze ima za posljedicu da deponovani CrN sloj sa metalno/poluprovodničkim
svojstvima, nakon V+ implantacije pokazuje izraziti metalni karakter.
Dvoslojni sistemi Co(50nm)/Si su pripremljeni u uslovima visokog vakuuma,
korišćenjem metode deponovanja potpomognutog jonskim snopom. Korišćene su
dvije vrste silicijumskih podloga: kristalne pločice orijentacije (100) i
podloge sa površinom amorfizovanom bombardovanjem sa niskoenergetskim Ar+
jonima. Nakon deponovanja slojevi su implantirani sa 400 keV Xe+ jonima do
doze 2×1015, 4×1015, 6×1015, 8×1015, 10×1015, 15×1015, 20×1015 i 30×1015
jona/cm2. Energija je odabrana tako da efekti jonske implantacije budu
najizraženiji na granici tanak sloj (Co)/podloga (Si). Deponovani i odabrani
implantirani slojevi (20×1015 Xe/cm2) su za</abstract><pub>University of Belgrade, Faculty of Physical Chemistry</pub><oa>free_for_read</oa></addata></record> |
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| subjects | CrN thin films IBM technique IBM tehnika ion implantation IR spectroscopy IR spektrofotometrija jonska implantacija RBS silicides silicidi tanki slojevi CrN TEM analiza TEM analysis XRD |
| title | Nanostructural characterization of CrN and CO thin films on silicon substrate, modified by ion bombardment |
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