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Minority carrier lifetime and diffusion length in type II superlattice barrier devices
摘要： The minority carrier lifetime in p-type InAs/GaSb type II superlattices (T2SLs) is quite short, typically in the region of tens of nanoseconds. In spite of this, T2SLs are becoming a viable alternative to Mercury Cadmium Telluride as the sensing material of choice for high end MWIR and LWIR infrared detectors. For example, SCD now manufactures a 640 × 512 format, 15 μm pitch LWIR focal plane array detector, with a quantum e?ciency close to 50%, a pixel operability of > 99.5%, and a dark current only about one order of magnitude larger than the state of the art Rule 07 value. A key to the very high performance of this detector is the use of an XBp barrier architecture that both suppresses the G-R current and allows stable passivation to all steps of the fabrication process. Since both the dark-current and photo-current in the XBp structure are di?usion limited, measurements of these quantities as a function of the device dimension provide an excellent vehicle for estimating the minority carrier lifetime and di?usion length, when performed in conjunction with k?p calculations of the T2SL density of states. Typical lifetime results are presented, which are consistent with values found by others using direct measurements. Di?usion lengths are reported in the range 3–7 μm, although these are not necessary limiting values.
关键词： Type II superlattice,Infrared detector,XBp detector,Di?usion length,InAs/GaSb superlattice,K?p model,Lifetime,Bariode
更新于2025-09-23 15:21:01
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Novel approach to passivation of InAs/GaSb type II superlattice photodetectors
摘要： The innovative two-step passivation by octadecanethiol (ODT) self-assembled monolayers (SAMs) and the following silicon dioxide (SiO2) deposition was used for the type-II InAs/GaSb superlattice photodetector. To understand the mechanism of passivation, the (100) GaSb surface covered with the ODT and, for comparison, with the biphenyl thiol (BPT), was characterized by the atomic force microscopy, Raman spectroscopy and contact angle analysis. The results of the study indicated the presence of the homogeneous both the ODT and the BPT monolayers; however, the ODT SAMs were more stable. Therefore, the ODT-based wet treatment was used in the two-step passivation resulting in a reduction of the dark current by one order of magnitude for passivated detector compared with an unpassivated device.
关键词： ODT,SiO2,InAs/GaSb superlattice,BPT,photodetectors,passivation
更新于2025-09-12 10:27:22
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Long wavelength type II InAs/GaSb superlattice photodetector using resonant tunneling diode structure
摘要： We report on a long wavelength type-II InAs/GaSb superlattice photodetector using resonant tunneling diode (RTD) structure. The linewidth of the satellite peak of the x-ray diffraction curve of the as-grown sample is only 15.7 arcsec showing a very high structural quality. The response maximum wavelength of the RTD detector is 7.5 μm and the 50% cutoff wavelength is 9.6 μm at 77 K. The measured QE is 147% at 7.5 μm when the applied bias voltage is 1.45 V and the corresponding responsivity is 8.9 A/W. This unusual QE is attributed to a large gain achieved when the device is under a resonant tunneling condition. The corresponding shot noise limited detectivity D* is 1.2×1010cm · Hz/W at 1.45 V at 77 K.
关键词： long wavelength,InAs/GaSb superlattice,quantum efficiency,resonant tunneling diode,type II
更新于2025-09-11 14:15:04
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Short/mid-wave two-band type II superlattice infrared heterojunction phototransistor
摘要： We report on a short/mid-wave (SW/MW) two-band type II InAs/GaSb superlattice (SL) infrared heterojunction phototransistor (HPT). The structure consists of two back-to-back HPTs for the SW and MW detections. At 77 K, the 50% cut-off wavelength of the SW and MW HPT is 2.6 and 4.2 (cid:22)m, respectively. When the applied bias voltage is 1.2 V, the responsivity is 213 A/W and the current gain is 611 for the SW band while for the MW band, the responsivity is 45.2 A/W and the current gain is 377 at bias voltage of 1.3 V. At 1.2 V, the shot noise limited detectivity D(cid:3) of the SW channel and the MW channel is 1.9(cid:2)1011 and 1.7(cid:2)109 cm(cid:1)Hz0:5/W, respectively.
关键词： two-band detection,Heterojunction phototransistor,current gain,type II InAs/GaSb superlattice
更新于2025-09-09 09:28:46