We study the electrical and optical properties of degenerate ZnGa2O4 films grown by metalorganic chemical vapor deposition (MOCVD) on sapphire and semi-insulating films grown by pulsed laser deposition (PLD) on fused silica. After a forming-gas anneal at 700 °C, the MOCVD film is highly conducting, with a room-temperature carrier concentration of 2 × 1020 cm−3, a mobility of 20 cm2/V s, and direct bandgap absorptions at 3.65 eV and 4.60 eV. Under the same annealing conditions, the PLD film is semi-insulating, with a direct bandgap absorption at 5.25 eV. The phonon structure, important for electrical and thermal conduction as well as superconductivity and other quantum phenomena, is very complicated due to the large number of atoms (and, thus, phonon branches) in the unit cell. However, we show that the phonon contributions to electron mobility (μph) can be directly measured by quantum-based magnetoconductivity over the temperature span T = 10–200 K. From an approximate analytical formula, μph = function (Tph, T), we calculate an effective phonon energy kTph(T) that takes account of all phonon contributions at temperature T. For T = 10–200 K, the value of kTph ranges from about 10 to 90 meV, consistent with the energy range of the ZnGa2O4 phonon density of states (at 0 K) calculated by density functional theory. The total measured mobility can then be modeled by μtot−1 = μii−1 + μph−1, where μii is the mobility due to ionized-impurity scattering. With a high bandgap, controllable conductivity, high breakdown voltage, and bulk-growth capability, ZnGa2O4 offers opportunities for high-power electronics and UV detectors.

中文翻译：

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简并半绝缘 ZnGa2O4 的电学和光学性质：通过量子磁导阐明电子/声子散射

我们研究了通过金属有机化学气相沉积 (MOCVD) 在蓝宝石上生长的简并 ZnGa2O4 薄膜和通过脉冲激光沉积 (PLD) 在熔融石英上生长的半绝缘薄膜的电学和光学特性。在 700 °C 的合成气退火后，MOCVD 膜具有高导电性，室温载流子浓度为 2 × 1020 cm-3，迁移率为 20 cm2/V s，直接带隙吸收为 3.65 eV 和4.60 电子伏特。在相同的退火条件下，PLD 薄膜是半绝缘的，直接带隙吸收为 5.25 eV。声子结构对于电传导和热传导以及超导和其他量子现象很重要，由于晶胞中有大量原子（以及声子分支），因此非常复杂。然而，我们表明，声子对电子迁移率 (μph) 的贡献可以通过温度跨度 T = 10–200 K 内基于量子的磁导率直接测量。 根据近似解析公式 μph = 函数 (Tph, T)，我们计算出考虑温度 T 下所有声子贡献的有效声子能量 kTph(T)。对于 T = 10–200 K，kTph 的值范围从大约 10 到 90 meV，与 ZnGa2O4 声子态密度的能量范围一致(在 0 K) 由密度泛函理论计算。然后可以通过 μtot−1 = μii−1 + μph−1 对总测量迁移率进行建模，其中 μii 是电离杂质散射引起的迁移率。ZnGa2O4 具有高带隙、可控电导率、高击穿电压和体生长能力，为大功率电子设备和紫外检测器提供了机会。