Atomistic modeling of energy band alignment in CdTe(1 0 0) and CdTe(1 1 1) surfaces

Autor: Walajabad S. Sampath, Aanand Thiyagarajan, Akash Shah, Anthony P. Nicholson, Umberto Martinez
Rok vydání: 2020
Předmět:
Zdroj: Applied Surface Science. 528:146832
ISSN: 0169-4332
DOI: 10.1016/j.apsusc.2020.146832
Popis: 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.
Databáze: OpenAIRE
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