Metal-insulator transitions in IZO, IGZO, and ITZO films

In this study, we measured the low-temperature resistivity of amorphous two- and three-dimensional (2D and 3D) indium-zinc oxide, indium-gallium-zinc oxide, and indium-tin-zinc oxide films with a wide range of carrier densities. To determine their critical characteristics at the metal-insulator tran...

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Veröffentlicht in:Journal of applied physics 2014-10, Vol.116 (15)
Hauptverfasser: Makise, Kazumasa, Hidaka, Kazuya, Ezaki, Syohei, Asano, Takayuki, Shinozaki, Bunju, Tomai, Shigekazu, Yano, Koki, Nakamura, Hiroaki
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Sprache:eng
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Zusammenfassung:In this study, we measured the low-temperature resistivity of amorphous two- and three-dimensional (2D and 3D) indium-zinc oxide, indium-gallium-zinc oxide, and indium-tin-zinc oxide films with a wide range of carrier densities. To determine their critical characteristics at the metal-insulator transition (MIT), we used the Ioffe–Regel criterion. We found that the MIT occurs in a narrow range between kFℓ = 0.13 and kFℓ = 0.25, where kF and ℓ are the Fermi wave number and electron mean free path, respectively. For films in the insulating region, we analyzed ρ(T) using a procedure proposed by Zabrodskii and Zinov'eva. This analysis confirmed the occurrence of Mott and Efros–Shklovskii (ES) variable-range hopping. The materials studied show crossover behavior from exp(TMott/T)1/4 or exp(TMott/T)1/3 for Mott hopping conduction to exp(TES/T)1/2 for ES hopping conduction with decreasing temperature. For both 2D and 3D materials, we found that the relationship between TMott and TES satisfies TES ∝ TMott2/3.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.4897501