Thermally self-consistent Monte Carlo simulation of InGaAs/AlGaAs HEMTs

Abstract

This paper presents results from the application of a thermally self-consistent Monte Carlo (MC) simulator to In/sub 0.15/Ga/sub 0.85/As/Al/sub 0.28/Ga/sub 0.72/As HEMTs. The simulator employs an iterative procedure which couples a MC electronic trajectory simulation with a fast Fourier series solution of the heat diffusion equation (HDE). Monte Carlo is one of the most accurate methods for simulating sub-micron semiconductor devices, as it is free from low-field, near-equilibrium approximations. In addition, the microscopic description of electron-phonon scattering in this method provides an inherent prediction of the spatial distribution of heat generation within a device. The thermal power distribution calculated from the net rate of phonon emission is fed to an HDE solver. The resulting temperature distribution is incorporated into the subsequent MC iteration. Electronic transport is simulated using three-valley spherical non-parabolic energy bandstructures. The simulations consider both the effect of optical and acoustic phonons mediating intravalley and intervalley electronic transitions. Ionised impurity, alloy disorder and electron-electron scattering processes are also included. The expected thermal droop is observed from the I-V characteristics of the simulated devices. Temperature distributions associated with different thermal power distributions are shown to be non-uniform with maximum values dependent upon the bias and the semiconductor die dimensions.