Bound exciton effect and carrier escape mechanisms in temperature-dependent surface photovoltage spectroscopy of a single quantum well

The temperature dependence of the surface photovoltage spectrum of a strained ${\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}/\mathrm{I}\mathrm{n}}_x{\mathrm{Ga}}_{1-x}\mathrm{A}\mathrm{s}/\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}$ single quantum well shows unusual broadening of the line shape around the $e_1{-\mathrm{h}\mathrm{h}}_1$ feature below 100 K. With evidence obtained from the temperature dependence of the photoluminescence spectrum, this unusual broadening is attributed to a bound exciton transition that is prominent at low temperatures. Selectively excited dc photocurrent experiments show that thermal emission and field-aided tunneling emission of photogenerated carriers from the quantum well are responsible for the charge separation and subsequent generation of surface photovoltage of the quantum well.