Modeling and Design Considerations of HgCdTe Infrared Photodiodes under Nonequilibrium Operation

Abstract

The general approach and effects of nonequilibrium operation of Auger suppressed HgCdTe infrared detectors are well understood. However, the complex relationships of carrier generation and dependencies on nonuniform carrier profiles in the device prevent the development of simplistic analytical device models with acceptable accuracy. In this work, finite element methods are used to accurately model the devices, including self-consistent, steady-state solutions of PoissonÕs equation and the carrier continuity equations for carrier densities, Boltzmann transport theory, and published models for recombination/generation processes in HgCdTe. Numerical simulations are used to optimize the material structure and doping levels for an Auger suppressed detector with k c = 5.5 lm at 200 K. The optimized detector structure with step doping and compositional profiles is then compared to a device with realistic gradient doping and compositional profiles.

Status of long-wave Auger suppressed HgCdTe detectors operating > 200 K

“…The Auger sup− pression is visible by negative differential resistance (NDR) in the reverse−bias current -voltage (I-V) characteristics. Auger GR suppression in active layer is reached by combi− nation of exclusion (P + /p or N + /n) and extraction (N + /p or P + /n) heterojunctions implemented into simple P + /n/N + or P + /p/N + architectures (where p and n stands for slightly p and n−type doping layers respectively) [12][13][14][15][16]. Those P + /p/N + , P + /n/N + configurations have demonstrated signifi− cant suppression of Auger GR mechanisms by reducing the absorber carrier density below thermal equilibrium in re− verse bias condition, however p−type (p) absorber offers better absorption coefficient and lower inherent Auger GR which should improve the detector's performance.…”

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

“…5,20 Moving forward, an extra highly doped contact layer in the nB n nn + or nB n pn + structure suppresses the Auger GR rate due to nonequilibrium operation (exclusion junction). [21][22][23] As far as nB n nn + and nB n pn + structures are concerned, the absorber-highly doped contact layer homojunction will be decisive, and it is believed that its optimization will allow the highest performance to be obtained (especially when including TAT/BTB processes at the n-n + and p-n + homojunction).…”

“…5,20 Moving forward, an extra highly doped contact layer in the nB n nn + or nB n pn + structure suppresses the Auger GR rate due to nonequilibrium operation (exclusion junction). [21][22][23] As far as nB n nn + and nB n pn + structures are concerned, the absorber-highly doped contact layer homojunction will be decisive, and it is believed that its optimization will allow the highest performance to be obtained (especially when including TAT/BTB processes at the n-n + and p-n + homojunction).In this paper we present the performance of BIRD MWIR HgCdTe detectors with a cutoff wavelength of k c = 5.2 lm at T = 200 K to 300 K. The temperature and bias voltage dependences of the dark current, R 0 A product, and detectivity of the BIRD HgCdTe detectors with an Auger suppression mechanism are analyzed, including both TAT and BTB processes at the exclusion homojunction.Finally, the performance of a state-of-the-art thermoelectrically (TE) cooled MWIR BIRD HgCdTe detector is compared with that of A III B V BIRD detectors. …”

Modeling and Simulation of High Operating Temperature MWIR Photo Detector Based on Mercury Cadmium Telluride

“…Steady-state numerical simulations of HgCdTe Auger-suppressed infrared photodiodes by using a Sentaurus Device, a commercial software package by Synopsis, were reported by Emilie et al [6][7][8]. In this paper, a comprehensive model of device was designed and simulated using ATLAS device software from SILVACO® for electrical characterization of the non-equilibrium MCT photo detectors.…”