Energy, temperature, and deposition angle dependence of Cd and Te2 deposited on CdTe

THIN SOLID FILMS

卷:697

Article

Khatri, Indiras¹  Amar, Jacques G.¹ 

[1] Univ Toledo, Dept Phys & Astron, Toledo, OH 43606 USA

关键词: CdTe;    Molecular dynamics;    Vapor deposition;    Close-spaced sublimation;   

DOI  :  10.1016/j.tsf.2020.137798

来源: Elsevier

【 摘 要 】

Cadmium Telluride (CdTe) is an important material for the production of high-efficiency thin-film solar cells. While sputter deposition has been used to create CdTe-based solar cells, two other important methods of growth are close-spaced sublimation and vapor deposition. In these methods, the depositing clusters correspond to Cd atoms and Te-2 dimers while the deposition energies are relatively low. In addition, depending on vapor pressure, deposition method, and target-substrate distance, deposition may occur at relatively large angles with respect to the substrate normal. Here we investigate the dependence of the attachment probability and deposition site for Cd and Te-2 clusters deposited on Cd-terminated and Te-terminated (100) and (111) surfaces of zincblende CdTe on deposition conditions. In general, we find that the deposition of Cd atoms and/or Te-2 dimers on the oppositely terminated surface leads to an attachment probability which is close to 1 and relatively independent of deposition conditions for both the (100) and (111) orientations. In contrast, deposition on the same terminated surface leads to a significantly lower attachment probability which generally decreases with increasing deposition angle, energy, and substrate temperature. Our results also indicate that deposition on the (111) surface leads to a significant excess Te sticking probability. In contrast, the excess Te attachment probability for deposition on the (100) surface is typically significantly smaller, and in some cases may even be negative. We also find, for both deposition on the (111) surface as well as opposite termination deposition on the (100) surface, that the dominant deposition mode corresponds to sitting on top of the surface which corresponds to growth of the next layer. In contrast, for same termination deposition on the (100) surface the dominant deposition mode corresponds to joining the first layer. These results imply that even for low deposition energies and substrate temperatures, deposition on the (100) surface is likely to create interstitials in the surface layer.

【 授权许可】

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