Exciton resonance induced dips in photocurrent spectra of weakly coupled GaAs/AlAs superlattice p–i–n diodes: barrier thickness dependence

Abstract Low-temperature photocurrent (PC) spectra of 100-period GaAs / AlAs superlattice p–i–n diodes with narrow electron miniband widths show negative PC peaks (dips) at the exciton resonance wavelengths under low field conditions. These dips observed at 17–100 K in the positive PC background are caused by the resonance-induced changes of the photogenerated carriers distribution within the thick intrinsic region and by the transit time effects on the vertical tunneling transport which is reduced with increasing the barrier thickness. Enhancement of the dip appearance at higher temperatures (up to 60 K) consistently explains the causes of the PC dips in terms of slowing down of the tunneling transport due to the thermal saturation of the drift velocity.