Extended short-wavelength infrared nBn photodetectors based on type-II InAs/AlSb/GaSb superlattices with an AlAsSb/GaSb superlattice barrier

Abstract

Extended short-wavelength infrared nBn photodetectors based on type-II InAs/AlSb/GaSb superlattices on GaSb substrate have been demonstrated. An AlAs0.10Sb0.90/GaSb H-structure superlattice design was used as the large-bandgap electron-barrier in these photodetectors. The photodetector is designed to have a 100% cut-off wavelength of ∼2.8 μm at 300 K. The photodetector exhibited a room-temperature (300 K) peak responsivity of 0.65 A/W at 1.9 μm, corresponding to a quantum efficiency of 41% at zero bias under front-side illumination, without any anti-reflection coating. With an R × A of 78 Ω·cm2 and a dark current density of 8 × 10−3 A/cm2 under −400 mV applied bias at 300 K, the nBn photodetector exhibited a specific detectivity of 1.51 × 1010 cm·Hz1/2/W. At 150 K, the photodetector exhibited a dark current density of 9.5 × 10−9 A/cm2 and a quantum efficiency of 50%, resulting in a detectivity of 1.12 × 1013 cm·Hz1/2/W.

Impact of temperature and gamma radiation on electron diffusion length and mobility in p-type InAs/GaSb superlattices

“…For the non-irradiated sample, there is an apparent shift in the trend of the minority electron mobility near 120 K shown in Fig. 4 which is characteristic of this T2SLS structure, 7,11,18,25 where a shift in the majority carrier mobility and density was observed for InAs/GaSb SLs with 8/8 and 9/ 9 periodic ML ratios. In those cases, the inflection was attributed to a shift in the dominant scattering mechanism from impurity scattering at low temperatures to phonon scattering at high temperatures.…”

“…InAs/GaSb-based type-II strain-layer superlattices (T2SLSs) have recently demonstrated great promise for infrared (IR) detection. 2,[7][8][9][10][11][12] Alternating InAs and GaSb layers of controlled thickness allow tuning of the narrow bandgap from 3 to 30 lm wavelength. The integrated unipolar barrier layer (B) reduces dark current, so that the detectors demonstrate detectivity comparable to conventional HgCdTe detectors.…”

Type–II superlattices base visible/extended short–wavelength infrared photodetectors with a bandstructure–engineered photo–generated carrier extractor

“…The superlattice was designed using the empirical tight–binding model (ETBM) 25 . The photo−generated carrier transport inside the absorption region relies entirely on diffusion; thus, the new photo–generated carrier extractor does not require the applied bias which is required by other unipolar photodetector structures, such as nBn and pMp 17,26,27 ; as such, it functions under zero bias like a conventional pn junction photodetector.

Figure 1Schematic diagram of conduction (E C ) and valence (E V ) bands of the visible/e–SWIR photodetector at 150K, with a bandstructure–engineered photo–generated carrier extractor. Section 1, 2, 3, 4, and 5 of the device have ~760, 580, 715, 1040, and 800 meV bandgap, respectively.

…”

“…As a developing material system, Type–II superlattices (T2SLs) have plenty of advantages for infrared detection and imaging including unique band gap engineering capability, lower costs for growth and manufacturing, suppression of auger recombination with reliable material uniformity over large grown area 14 – 16 . T2SLs have recently demonstrated coverage of the e−SWIR spectral region 17 – 24 , however, there have been no reports of visible/infrared photodetectors based on the T2SLs material system.…”

Mid-wavelength Infrared Avalanche Photodetector with AlAsSb/GaSb Superlattice

“…The AlGaAsSb barrier layer in the MQW structure was grown as an AlAs0.1Sb0.9/GaSb superlattice, This SLS is called an H-structure superlattice and can be used as an electron barrier layer in some type-Ⅱ superlattice infrared photodetector designs. [19] For convenience, 'AlGaAsSb' will be used to refer to the AlAsSb/GaSb H-structure superlattice in the rest of discussion. The bandgap energy of the Hstructure superlattice was calculated by the empirical tight-binding method (ETBM) to be around 1 eV at 150 K. The effective conduction band of the H-structure superlattice moves upward significantly due to the confinement of the electrons in the GaSb well by the AlAsSb barrier layers.…”