Electrooptical Characterization of MWIR InAsSb Detectors

Abstract

InAs 1-x Sb x material with an alloy composition of the absorber layer adjusted to achieve 200K cutoff wavelengths in the 5 µm range has been grown. Compound-barrier (CB) detectors were fabricated and tested for optical response and J dark -V d measurements were acquired as a function of temperature. Based on absorption coefficient information in the literature and spectral response measurements of the midwave infrared (MWIR) nCBn detectors, an absorption coefficient formula α(Ε, x, T) is proposed.Since the presently suggested absorption coefficient is based on limited data, additional measurements of material and detectors with different x values and as a function of temperature should refine the absorption coefficient, providing a more accurate parametrization. Material electronic structures were computed using a k•p formalism. From the band structure, dark current density (J dark ) as a function of bias (V d ) and temperature (T) were calculated and matched to J dark -V d at fixed T and J dark -T at constant V d curves. There is a good match between simulation and data over a wide range of bias, but discrepancies that are not presently understood exist near zero bias.a. e-mail: arvind.d'

Theoretical Modeling of HOT HgCdTe Barrier Detectors for the Mid-Wave Infrared Range

“…Figure 18 shows the simulated J DARK versus the operating temperature for the MWIR BIRD HgCdTe structures (k c = 5.2 lm, T = 200 K) in comparison with experimental dark current densities for the following detectors: InAs/GaSb with AlGaSb barrier T2SL nB p n (k c = 5.4 lm, T = 230 K), InAsSb with AlAsSb barrier (k c = 5.05 lm, T = 200 K), and the HOT HgCdTe nB n n detector (x = 0.3). 17,[28][29][30] The particular significance of the incorporation of the extra barrier for carriers (n + ) in the BIRD nB n nn + structures versus the single barrier (potential majority-carrier blocking) is clearly evident from the J DARK decrease from 3 A/cm 2 to 7 9 10 À3 A/cm 2 and 40 A/cm 2 to 3 A/cm 2 for T = 200 K and T = 300 K, respectively. Proper contact layer arrangement increases the operating temperature by close to 75 K for V = 0.4 V. The absorber's p-type doping (assuming the same level of doping N D = N A = 10 14 cm À3 ) leads to a further decrease of J DARK to the level of 4 9 10 À3 A/cm 2 and 2 A/cm 2 for T = 200 K and T = 300 K, respectively.…”

“…Figure 18 shows the simulated J DARK versus the operating temperature for the MWIR BIRD HgCdTe structures (k c = 5.2 lm, T = 200 K) in comparison with experimental dark current densities for the following detectors: InAs/GaSb with AlGaSb barrier T2SL nB p n (k c = 5.4 lm, T = 230 K), InAsSb with AlAsSb barrier (k c = 5.05 lm, T = 200 K), and the HOT HgCdTe nB n n detector (x = 0.3). 17,[28][29][30] The particular significance of the incorporation of the extra barrier for carriers (n + ) in the BIRD nB n nn + structures versus the single barrier (potential majority-carrier blocking) is clearly evident from the J DARK decrease from 3 A/cm 2 to 7 9 10 À3 A/cm 2 In addition, having taken the difference in the absorber's composition into consideration, we may assume that the presented results coincide with these published by Velicu et al 17,28 Comparing the nB n n and nB n p detectors, it is clearly evident that the SRH contribution is totally suppressed for the n-type absorber structures (diffusion limited), while the p-type absorber architecture exhibits a twoslope behavior with a crossover temperature estimated at the level of T c = 227 K. Both nB n nn + and nB n pn + detectors are diffusion limited (one-slope behavior). Figure 19 compares the R 0 A (k B T/q/J s ; V = 1 mV for BIRD structures) product for nB n n, nB n nn + , and nB n nN + (the N + layer, similarly to the barrier, consists of two sublayers-the very first one fitted with a graded composition to the absorber and the second with x = 0.4) versus the values given by ''Rule 07,'' being a simple means to compare mercury cadmium telluride (MCT) IR detectors.…”

The complete absorption spectra of InAs0.87Sb0.13 films grown by liquid phase epitaxy

“…High quality InAs 0.87 Sb 0.13 epilayer was achieved by LPE through introducing intermediate composition InAs 0.92 Sb 0.08 as buffer layer to accommodate the large lattice mismatch between InAs 0.87 Sb 0.13 epilayer and InAs substrate. The band-to-band optical absorption is important to understanding the infrared optical absorption of InAs 1−x Sb x film, and it also plays an important role in optimizing the absorber layer thickness of multilayer device architecture [5]. For proper device design, detailed and accurate optical parameters such as absorption coefficient, energy band gap are also desired [6].…”

“…For proper device design, detailed and accurate optical parameters such as absorption coefficient, energy band gap are also desired [6]. However, there are few reports on the research of the optical absorption properties for InAs 1−x Sb x material besides a little theory calculation work [5].…”

Nanopillar optical antenna nBn detectors for subwavelength infrared pixels

“…The current approaches to detectivity improvement for HOT have been focused on Auger suppression to increase lifetime 2-4 and nBn bandstructure 5 to achieve diffusion limited performance and eliminate G-R current of the photodetector. A more recent approach to enhancing the SNR (or detectivity) of a photodetector is by using antenna structures to collect photons from a larger area and funnel into subwavelength absorber 6 . Planar IR detectors are fundamentally limited by the lateral junction area being equivalent with the optical collection.…”