Monte Carlo simulation of electron transport in mercury cadmium telluride

Abstract

We derive expressions for electron scattering rates in mercury cadmium telluride accounting for correct wave functions in narrow-band-gap materials. These scattering rates differ slightly from the rates obtained from standard expressions for wide-band-gap materials. The difference is related to spin-flip processes and has a relatively small effect on the transport properties. However, it is very important for spin-orientation phenomena. Monte Carlo simulations have been performed to investigate the mobility and steady state velocity-field characteristics of electron transport in mercury cadmium telluride with x=0.205 at 77 K. The simulations include scattering by polar optical phonons, ionized impurities, and alloy scattering. The Pauli exclusion principle as well as the dependence of the screening length on the distribution function have been accounted for. The simulations show that the screening length increases with increasing electric field with this dependence being the strongest for low carrier concentrations. For n = 5.4 × 1015 cm−3, the inclusion of the Pauli exclusion principle and varying screening length reduces the electron velocity by 5% to 10% depending on the electric field. Velocity-field curves are in good agreement with experimental data up to the electric field where the impact ionization becomes important. We have also calculated the dependence of low-field mobility on the electron concentration, which shows reasonable agreement with experimental data.

Full-Band Monte Carlo Simulation of HgCdTe APDs

“…We introduce polar-optical phonon scattering by considering two different polar-optical phonon modes, corresponding to CdTe or HgTe sublattices. 20,23 In the present work, we follow the approach described in Ref. 39, which is equivalent to the model reported in Ref.…”

“…Mobility computations suggest that the alloy scattering potential for electrons can be computed as the conduction-band offset DE c ¼ 1:45 eV; whereas the alloy scattering for holes is determined by the valence-band offset DE v ¼ 0:35 eV. 2,20 The empirical selection of a constant alloy scattering potential can be replaced by a more fundamental approach, based on detailed information about the electronic structure and the corresponding screened atomic potentials. 40 In the present work we employ the empirical alloy scattering potentials used by Gelmont et al, 20 postponing first-principles calculations of alloy scattering to a future paper.…”

“…2,20 The empirical selection of a constant alloy scattering potential can be replaced by a more fundamental approach, based on detailed information about the electronic structure and the corresponding screened atomic potentials. 40 In the present work we employ the empirical alloy scattering potentials used by Gelmont et al, 20 postponing first-principles calculations of alloy scattering to a future paper. The computed alloy scattering rate for electrons is presented in Fig.…”

A 2D Full-Band Monte Carlo Study of HgCdTe-Based Avalanche Photodiodes

“…5,27 In the present work the alloy scattering potential for electrons (and holes) was computed using an effective scattering potential equal to the conduction band (valence band for holes) offset between HgTe and CdTe. 28 The impact ionization transition rate was obtained by first-order perturbation theory from the band diagram and the corresponding momentum-dependent dielectric function. [29][30][31][32][33] In Ref.…”

Hydrodynamic modelling of electron transport in submicron Hg0.8Cd0.2Te diodes

“…The consequence of this alloy proportion is a narrow semiconductor band-gap of about 0.1 eV: in particular, degeneracy and impact ionization processes are activated from low electric fields of the order of 100 V/cm [4]. Despite of his wide interest, few results are available in the literature concerning a physical modelling of transport in MCT-based devices.…”