Influence of the recharging process on the dark current noise in quantum-well infrared photodetectors

Abstract

We show that the dark current noise spectrum of an In(0.30)Ga(0.70)As/GaAs quantum-well infrared photodetector (QWIP) is characterized by two plateau-like frequency regions. At high frequencies, the observed noise current is due to the generation-recombination noise of carriers, which have been emitted thermionically from the quantum wells into the continuum. In the low-frequency regime, an additional contribution to the noise current is caused by the redistribution of space charges, that occurs on a time scale similar to the dielectric relaxation time

Non-Gaussian noise in quantum wells infrared photodetectors

“…It should be noted that the spectral behavior illustrated in Fig. 1 is very similar to that reported recently for an n-type device, where the observed cut-off has been ascribed to recharging processes [14].…”

“…In principle, higher moments, beyond the 2-point correlations should be measured and analyzed. Nevertheless, the results of the time domain measurements allow us to conclude that the low frequency cut-off can be attributed to two bias dependent average life times, s up and s dn , in two distinct states of the system rather than to a single time constant of the recharging process, as suggested in the literature [10,14].…”

“…8. A non-monotonic capture probability has been already measured before and few theoretical works attribute it to tunneling or inter-valley scattering [14,22,23]. Moreover non-uniform electric field distribution was already invoked in the past in order to explain deviation of noise measurements from the simple generation recombination noise theorem [24,25].…”

“…However, GR noise in QWIPs should be low-pass filtered at much lower cut-off frequency related to the QWIP time constant RC. The time constant is determined by the contacts resistance and device capacitance [10,14,17]. The device dependent cut-off frequency corresponds to the inverse of the recharging time of depleted wells [14].…”

“…Noise in quantum well infrared photodetectors (QWIPs) was studied extensively in the last years [2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Generationrecombination (GR) noise, closely related to the usual GR noise in classical photodetectors, [16] has been accepted as a dominant noise mechanism in QWIPs.…”