Hydride vapor phase epitaxy of Si-doped AlN layers using SiCl4 as a doping gas

•Si-doped AlN layers were grown by HVPE using SiCl4 as a doping gas.•Linear control of Si concentration was achieved.•Pit- and stress-free Si-doped AlN layers were obtained on bulk AlN substrates.•Si-doped layers showed n-type conductivity with an activation energy of 253 meV.•Introduction of Al vac...

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Veröffentlicht in:Journal of crystal growth 2020-09, Vol.545, p.125730, Article 125730
Hauptverfasser: Yamamoto, Reo, Takekawa, Nao, Goto, Ken, Nagashima, Toru, Dalmau, Rafael, Schlesser, Raoul, Murakami, Hisashi, Collazo, Ramón, Monemar, Bo, Sitar, Zlatko, Kumagai, Yoshinao
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Sprache:eng
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Zusammenfassung:•Si-doped AlN layers were grown by HVPE using SiCl4 as a doping gas.•Linear control of Si concentration was achieved.•Pit- and stress-free Si-doped AlN layers were obtained on bulk AlN substrates.•Si-doped layers showed n-type conductivity with an activation energy of 253 meV.•Introduction of Al vacancy related acceptors compensated the n-type carriers. Growth of Si-doped AlN layers by hydride vapor phase epitaxy on AlN/sapphire templates prepared by metalorganic vapor phase epitaxy and bulk AlN substrates prepared by physical vapor transport was investigated using silicon tetrachloride (SiCl4) as a doping gas. On the AlN/sapphire templates, when the SiCl4 supply was low, the incorporation ratio of Si decreased due to the influence of O impurities resulting from the decomposition of the sapphire. In addition, pits were formed on the surfaces, and the pit density increased significantly at Si concentrations exceeding 2 × 1019 cm−3. In contrast, on the bulk AlN substrates, the Si concentration increased linearly with increasing SiCl4 supply, and a pit- and stress-free layer could be grown with a Si concentration as high as 6.5 × 1019 cm−3. Hall effect measurements revealed that this layer exhibited n-type conductivity with a donor activation energy of 253 meV. However, the carrier density at room temperature (RT) was as low as 3.6 × 1013 cm−3 because of the high compensation ratio due to the presence of acceptors. A broad peak centered at 3.3 eV was observed in the RT photoluminescence spectra of the Si-doped AlN layers grown on the bulk AlN substrates, indicating that Al vacancies formed by the Fermi level effect due to Si doping acted as acceptors that compensated for carriers.
ISSN:0022-0248
1873-5002
DOI:10.1016/j.jcrysgro.2020.125730