15 December 2000 Electrical properties of ZnS, CdTe/HgCdTe interfaces evaporated from effusion cell in UHV chamber
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ZnS and CdTe layers are deposited by thermal evaporation on HgCdTe epilayers with xequals0.23 grown by MOCVD. Thermal evaporation is performed from commercial effusion cell in UHV chamber. The evaporation sources are ZnS and CdTe. Electrical properties of the ZnS/HgCdTe and CdTe/HgCdTe are determined by capacitance-voltage characteristics of metal- insulator-semiconductor test devices. It is found that the HgCdTe surface is slightly accumulated and the interface charge density of the order of low 1011cm-2 in both ZnS/HgCdTe and CdTe/HgCdTe structure. In the case of CdTe deposition, best results are obtained when the deposition rate is extremely slow of around 0.2A/sec. With this slow deposition rate, there is possibility of unintentional contamination from the residual gas in vacuum chamber into growing films. Thus, evaporation in a UHV environment is necessary for a sufficiently clean layer. The effect of Cd overpressure on surface charge of HgCdTe is presented. The main features of the ZnS and CdTe deposited from effusion cell in UHV chamber are low fixed surface charge density, and small hysteresis. The good electrical properties of the interface, thermal stability and chemical properties of ZnS and CdTe grown with very slow rate under ultra-high vacuum suggest that these layers can be applied for improving the surface passivation of photovoltaic devices fabricated on HgCdTe.
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Jin-Sang Kim, Jin-Sang Kim, Jong-Hyung Song, Jong-Hyung Song, Sang-Hee Suh, Sang-Hee Suh, "Electrical properties of ZnS, CdTe/HgCdTe interfaces evaporated from effusion cell in UHV chamber", Proc. SPIE 4130, Infrared Technology and Applications XXVI, (15 December 2000); doi: 10.1117/12.409836; https://doi.org/10.1117/12.409836


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