Photoluminescence of CdSe: The effect of photoetching

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Abstract
The photoetching of single crystal n-type CdSe was investigated, using photoluminescence at room temperature and at 77 K. A blue shift is observed in the photoluminescence spectrum of crystals when the doping density is decreased. It is explained through the decrease in density of bound excitons and donor-acceptor pairs when the impurity concentration decreases. A similar blue shift is observed for crystals which were photoetched and is attributed to the preferential etching of dopant atoms (vacancies) near the semiconductor surface. This observation is supported by the dependence of the photoluminescence on the electrode potential. Consequences of our findings on the performance and stability of photovoltaic (photoelectrochemical) cells are discussed.