Atomistic modeling of energy band alignment in CdTe(1 0 0) and CdTe(1 1 1) surfaces
Atomistic modeling of energy band alignment in CdTe(1 0 0) and CdTe(1 1 1) surfaces
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DOI：
10.1016/j.apsusc.2020.146832
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发表时间：
2020-10
影响因子：
6.7
通讯作者：
A. Nicholson;U. Martinez;Akash Shah;A. Thiyagarajan;W. Sampath
中科院分区：
文献类型：
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作者：
A. Nicholson;U. Martinez;Akash Shah;A. Thiyagarajan;W. Sampath
碲化镉表面的能带排列的原子尺度的角度还没有空间上的研究，尽管主要的作用表面发挥在形成界面内的碲化镉薄膜光伏器件。基于密度泛函理论和表面绿色函数的原子模型被用于计算碲化镉表面的能带排列。CdTe（1 0 0）（（1 × 1）和c（2 × 2）重构）和CdTe（1 1 1）（（1 × 1）和（2 × 2）重构）晶面在没有和具有表面弛豫的情况下提供了影响电荷载流子输运的有洞察力的能带弯曲特性。结果表明，非弛豫的（1 × 1）CdTe（1 0 0）和CdTe（1 1 1）表面使价带向下弯曲，表面极性决定表面势的大小.重构的CdTe（1 0 0）c（2 × 2）和CdTe（1 1 1）（2 × 2）表面相对于未重构的变体具有良好的表面电子特性。此外，结构弛豫的CdTe（111）表面产生内部能量尖点电势，其可以增强空穴电荷朝向CdTe太阳能电池器件背面的传输。能带对齐计算内的研究导致详细了解碲化镉表面可能会影响碲化镉薄膜光伏应用。
An atomic-scale perspective of energy band alignment in CdTe surfaces has not been spatially studied despite the major role surfaces play in forming interfaces within CdTe-based thin film photovoltaic devices. Atomistic modeling based on density functional theory coupled with surface Green’s function is used for calculating energy band alignment of CdTe surfaces. The CdTe(1 0 0) ((1 × 1) and c(2 × 2) reconstruction) and CdTe(1 1 1) ((1 × 1) and (2 × 2) reconstruction) facets without and with surface relaxation provide insightful band bending characteristics that influence charge carrier transport. Results show that unrelaxed (1 × 1) CdTe(1 0 0) and CdTe(1 1 1) surfaces bend the valence band downward with surface polarity dictating the surface potential magnitude. The reconstructed CdTe(1 0 0) c(2 × 2) and CdTe(1 1 1) (2 × 2) surfaces result in favorable surface electronic features in relation to their unreconstructed variants. In addition, the structurally relaxed CdTe(1 1 1) surfaces develop an internal energy cusp potential that may enhance hole charge transport toward the back of CdTe solar cell devices. Energy band alignments calculated within the study lead to a detailed understanding of how CdTe surfaces may affect CdTe-based thin film photovoltaic applications.