Generation-Recombination Effect in MWIR HgCdTe Barrier Detectors for High-Temperature Operation

Abstract

An advanced numerical model was applied to investigate dark current-voltage characteristics of high operating temperature (HOT) HgCdTe p + B p nN + and p + B p pN + barrier detectors operated in midwave infrared spectral range. In addition to diffusion mechanisms, all assumed generation-recombination effects, including Shockley-Read-Hall (SRH) mechanism associated with metal site vacancies and dislocations, tunneling, and impact ionization, allow more precise interpretation of obtained experimental results. Investigated structures have the same cap-barrier structural unit (pB p ) and N + bottom contact layer but a different n-and p-type absorption layer optimized at cutoff wavelength up to 3.6 µm at 230 K. Both type barrier detectors exhibit very low experimental dark currents, in the range of 2-3 × 10 −4 A/cm 2 at 230 K. Calculations show that currents in the device with the n-type absorber are limited by Auger processes while currents in the device with the p-type absorption layer are mainly associated with SRH mechanisms. A reduction of the thermal generation rate in a wide bandgap barrier is observed. The presence of the enhanced electric field in the depletion regions increases trap-assisted tunneling via traps located at dislocation cores. In high-quality materials, with a reduced number of structural defects, the device with p-type absorption layer should provide lower dark currents in HOTs.Index Terms-Barrier infrared (IR) detectors, dark current, generation-recombination (GR) effect, HgCdTe, high operating temperature (HOT).

Numerical estimation of photon reabsorption process and optical crosstalk in arrays of HgCdTe photodiodes

“…Polarization in the reverse direction suppresses recombination much stronger than generation. The rate of recombination is more strongly dependent on the concentration of carriers than the generation rate (Kopytko and Jóźwikowski 2015;Józwikowski et al 2010). NEMO gives effects like strong cooling.…”

The Numerical–Experimental Enhanced Analysis of HOT MCT Barrier Infrared Detectors

“…Moreover, with the increase in the reverse bias voltage, the SHR generation is increased due to TAT. 18 Exclusion, however, has a very strong influence on the thermal generation in LWIR structures. This is due to the fact that the thermal generation is mainly caused by Auger mechanisms in the absorber area.…”

“…In Ref. 18, we conducted an extensive discussion of the impact of different mechanisms of G-R on j(V) characteristics in barrier detectors. A detailed description of parameters for SHR, Auger 1 and Auger 7 lifetimes is included in Ref.…”

“…A detailed description of parameters for SHR, Auger 1 and Auger 7 lifetimes is included in Ref. 18 and references cited here. Carrier mobility is calculated theoretically as it was presented in Ref.…”

Langevin-like method for modelling the noise currents in HgCdTe barrier LWIR detectors

“…G-R processes are influenced by Auger 1 and Auger 7 interband mechanisms and enhanced additionally by SHR processes caused by metal vacancies and dislocations (Kopytko and Jóźwikowski 2015). Other symbols are explained in (Jóź-wikowski et al 2016).…”