Electron transport studies on In(0.30)Ga(0.70)As/GaAs-quantum-well infrared photodetectors using time-resolved photocurrent measurements

We report on the time-resolved photocurrent response on an InGaAs/GaAs quantum-well infrared photodetector stimulated by infrared fs-laser pulses (~9 µm wavelength). We observe two dynamic photocurrent components, which are driven by the optical excitation and by the photoinduced space charge, respectively. The ratio of the time-averaged values of these two components allows us to determine the photoconductive gain. These gain values exhibit a good quantitative agreement with the gain obtained from continuous waves measurements of the peak responsivity. Furthermore, we present a detailed study of the decay time constant of the slow component as a function of the temperature and the bias voltage and compare our results with a recent theoretical model.