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. 2019 Feb 4;9(1):1290.
doi: 10.1038/s41598-018-38419-0.

Classical and quantum conductivity in β-Ga2O3

David C Look  1   2 , Kevin D Leedy  3
Affiliations

Classical and quantum conductivity in β-Ga2O3

David C Look et al. Sci Rep. .

Abstract

The conductivity σ, quantum-based magnetoconductivity Δσ = σ(B) - σ(0), and Hall coefficient RH (= µH/σ) of degenerate, homoepitaxial, (010) Si-doped β-Ga2O3, have been measured over a temperature range T = 9-320 K and magnetic field range B = 0-10 kG. With ten atoms in the unit cell, the normal-mode phonon structure of β-Ga2O3 is very complex, with optical-phonon energies ranging from kTpo ~ 20-100 meV. For heavily doped samples, the phonon spectrum is further modified by doping disorder. We explore the possibility of developing a single function Tpo(T) that can be incorporated into both quantum and classical scattering theory such that Δσ vs B, Δσ vs T, and µH vs T are all well fitted. Surprisingly, a relatively simple function, Tpo(T) = 1.6 × 103{1 - exp[-(T + 1)/170]} K, works well for β-Ga2O3 without any additional fitting parameters. In contrast, Δσ vs T in degenerate ScN, which has only one optical phonon branch, is well fitted with a constant Tpo = 550 K. These results indicate that quantum conductivity enables an understanding of classical conductivity in disordered, multi-phonon semiconductors.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1
Figure 1
Square of absorption coefficient α vs energy E for βGAO. The intercept of α2 vs E gives a direct energy gap of 4.57 eV.
Figure 2
Figure 2
Conductivity σ, Hall-mobilty µ, and free-electron concentration n, vs temperature T in βGAO. The lines are theoretical fits of µ vs T under three possible conditions: (1) Tpo(T) = 1.4 × 103 K; (2) Tpo(T) = 1.0 × 103 K; or (3) Tpo(T) = 1.6 × 103{1 − exp[−(T + 1)/170]} K.
Figure 3
Figure 3
Magnetoconductivity Δσ vs T, B = 10 kG, for βGAO and thin-film ScN. The ScN is well fitted with a constant Tpo = 550 K, but the βGAO requires a function Tpo(T) = 1.6 × 103{1 − exp[−(T + 1)/170]} K.
Figure 4
Figure 4
Experimental points: the required value of Tpo to fit Δσ vs T, B = 10 kG, at each temperature T, for βGAO. Solid line: a fit of Tpo vs T, giving Tpo(T) = 1.6 × 103{1 − exp[−(T + 1)/170]} K.
Figure 5
Figure 5
Experimental points: magnetoconductivty Δσ = σ(B) - σ(0) at temperatures T = 9, 15, 20, and 25 K. Solid lines: theoretical fits with Tpo(T) = 1.6 × 103{1 − exp[−(T + 1)/170]} K.
See this image and copyright information in PMC

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