Analysis of Extended Threshold Wavelength Photoresponse in Nonsymmetrical p-GaAs/AlGaAs Heterostructure Photodetectors

Analysis of Barrier Parameters on the Extended Threshold Wavelength of Infrared Detectors

“…However, with flat high energy barrier, hot holes with energy corresponding to only higher potential barrier can overcome the barrier. Thus, it is expected that efficiency of the hot -cold hole interaction in the absorber decreases for SP1001 which could be the prime mechanism of extended threshold wavelength in SP1001 and SP1007 [6]. Therefore, photoresponse with clear eff observed in SP1007 even at a small value of the electric field as compared to SP1001.…”

“…However upon application of bias, t = 1.24/ observed with slight variation in t with increasing bias due to image force induced barrier lowering effect [10]. The interaction of hot holes and cold holes (holes which are already present in p-GaAs absorber due to doping) in the absorber leads to mechanism responsible for extended threshold wavelength in detectors SP1001, SP1007 and 15SP3 as already mentioned in details in Ref [6].…”

“…Finally, the escape of hot carriers from that quasi-Fermi level across the collector barrier when a long wavelength photon is absorbed gives the extended wavelength threshold photoresponse eff ( eff . >> t ) [6]. However, in conventional heterostructure detectors with E v = 0, spectral photoresponse with designed t have been observed.…”

“…The photo-absorption in the p-GaAs absorber excites hot carriers from the light/heavy hole bands into the split-off band [3], and these excited carriers then escape into the barrier region, typically interact with cold carriers and are collected at the contact region. The basic model to explain the eff in IR detectors is based on the hot carrier effects [4][5][6]. In that kind of IR detectors, for a net flow of hot carriers E v is critical and increasing E v and the gradient of the injector barrier; will increase the carrier flow.…”

Recent Progress on Extended Wavelength and Split-Off Band Heterostructure Infrared Detectors

“…A reference photodetector without the offset and cannot show the extended wavelength mechanism is also shown in Figure 5A. The mechanism responsible for the extension of threshold wavelength in heterostructure detectors has been analyzed by Somvanshi et al [93], which is based on the hot carrier effects in the semiconductor heterostructures [94][95][96]. The hot carrier effect is principally governed by the carrier-carrier and carrier-phonon scattering processes and has been widely studied in the past [96][97][98].…”