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The Influence of Dopant and Substrate Temperature on the Current-Volltage Characteristics for CdTe/P-GaAs Heterojunction

F.Y. Al- Shaikley, M.F.A.Alias, A.A.Alnajjar, A.A.J.Al-Douri

Thin films of undoped and doped CdTe with thickness around 500±10nm were deposited by thermal evaporation technique onto (100) p-GaAs wafer. The effect of both Al and Sb dopant percentages (0.5, 1.5 and 2.5) and substrate temperatures (RT and 423K) on the optoelectronic properties of CdTe/p-GaAs heterojunction was studied. IV characteristics under illumination for the prepared CdTe/p-GaAs heterojunctions showed a good significant photovoltaic effect. The value of short circuit current (Isc) for CdTe/p-GaAs heterojunction doped with Sb was higher than that doped with Al. The effect of Al doping on the value of the open-circuit voltage (Voc) was more than Sb doped. The outcomes of all these measurements for various (Al and Sb)doping of thin CdTe deposited on GaAs were indicated that 2.5%Sb-doped CdTe/p-GaAs heterojunctions deposited at RT and 423K posses a good response to illumination which make it a candidate for heterojunction device used as basic for fabricating photo sensors