Ultrafast intersubband photocurrent response in quantum-well infrared photodetectors

Abstract

We report on a high bandwidth measurement of the transient intersubband photocurrent of a GaAs/AlGaAs multiple quantum-well infrared photodetector (QWIP). The photocurrent is excited via tunable subpicosecond infrared pulses. The response time of the detector has a full width at half-maximum of 18.5 ps and a rise time of 14.5 ps, which is limited by the electrical circuit. The decay time of the photocurrent response exhibits a significant dependence on the applied voltage, with increasing decay times for increasing bias voltages. From the experimental data, we conclude that the intrinsic response time of a QWIP is less than 7 ps

Ultrafast Phenomena in Semiconductors

“…There are numerous studies of n-type quantum well detectors in the literature [219][220][221][222][223][224][225][226][227][228][229][230][231][232][233], starting from the early work reported in [18]. Recently, infrared detections of about 5 x 1010 cmHzl/2 W-I [226] and 256 x 256 pixel arrays [232] have been reported for operation at 77 K. For a recent review of this field including a discussion of infrared detectivities, the reader is referred to [233] and the references therein.…”

Analytical model of transient photoresponse of quantum well infrared photodetectors

“…Recently, QWIP high-speed photoresponse was studied using short infrared pulses from a CO 2 laser. 13,14 Intrinsic response time of a QWIP was estimated to be less than 7 ps. 14 Several mechanisms limiting the QWIP response time have been suggested in the literature, such as transit time effect 6 or carrier capture time to the QWs.…”

“…13,14 Intrinsic response time of a QWIP was estimated to be less than 7 ps. 14 Several mechanisms limiting the QWIP response time have been suggested in the literature, such as transit time effect 6 or carrier capture time to the QWs. 9 These effects, however, can not explain very slow photocurrent transients in QWIPs under low-background operation and at low temperatures.…”

Electron transport studies on In0.30Ga0.70As/GaAs-quantum-well infrared photodetectors using time-resolved photocurrent measurements

“…Beyond FPAs, QWIPs are interesting for high-speed applications since their internal photocurrent response times are very short, with an intrinsic carrier lifetime of less than 7 ps. 3 This property makes QWIPs ideally suited for heterodyne spectroscopy, since a detector bandwidth of at least 20 GHz is necessary to provide a continuous tunability when using individual lines of a CO 2 laser. In order to optimize high-frequency operation, the understanding of the carrier transport mechanism in QWIPs is inevitable.…”