Amorphous mixed-anion semiconductors (AMASs) such as amorphous zinc oxynitride and amorphous zinc oxysulfide (a-ZnOS) have attracted attention as rare-metal-free amorphous semiconductors that exhibit electron mobility comparable to or greater than the electron mobilities of typical amorphous oxide semiconductors (AOSs), including amorphous In–Ga–Zn–O (a-IGZO). A characteristic feature of AMASs is that their conduction-band minimum (CBM) mainly consists of s-orbitals of the single cation, in contrast to conventional AOSs, whose CBM is composed of s-orbitals of multiple cations. This unique band structure suggests that the potential of carrier electrons in AMASs exhibits less spatial fluctuation than that of carrier electrons in AOSs. In this study, we analyzed the temperature dependence of the electron transport properties of a-ZnOS thin films using the random barrier model to evaluate the potential barrier height and its spatial variation. The analyses revealed that the barrier height of a-ZnOS is comparable to that of a-IGZO. This result was attributed to the large covalent nature of Zn–S bonds strongly influencing the potential at the CBM through the antibonding interaction.

中文翻译：

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非晶氧硫化锌薄膜中的电子传输机制

非晶混合阴离子半导体 (AMAS)，例如非晶氮氧化锌和非晶氧硫化锌 (a-ZnOS)，作为不含稀有金属的非晶半导体，其电子迁移率与典型非晶氧化物半导体的电子迁移率相当或更高，因此备受关注(AOSs)，包括非晶 In-Ga-Zn-O (a-IGZO)。AMAS 的一个特征是它们的导带最小值 (CBM) 主要由单个阳离子的s轨道组成，而传统的 AOS 的 CBM 由s组成-多个阳离子的轨道。这种独特的能带结构表明，AMAS 中载流子电子的电势比 AOS 中载流子电子的空间波动小。在这项研究中，我们使用随机势垒模型分析了 a-ZnOS 薄膜电子传输特性的温度依赖性，以评估势垒高度及其空间变化。分析表明 a-ZnOS 的势垒高度与 a-IGZO 相当。这一结果归因于 Zn-S 键的大共价性质通过反键相互作用强烈影响 CBM 的潜力。