Electron Heat Source Driven Heat Transport in GaN at Nanoscale: Electron-Phonon Monte Carlo Simulations and a Two Temperature Model.

Anish Muthukunnil Joseph,Bingyang Cao

doi:10.3390/ma15051651

Abstract

The thermal energy transport in semiconductors is mostly determined by phonon transport. However in polar semiconductors like GaN electronic contribution to the thermal transport is non-negligible. In this paper, we use an electron–phonon Monte Carlo (MC) method to study temperature distribution and thermal properties in a two-dimensional GaN computational domain with a localized, steady and continuous electron heat source at one end. Overall, the domain mimics the two-dimensional electron gas (2DEG) channel of a typical GaN high electron mobility transistor (HEMT). High energy electrons entering the domain from the source interact with the phonons, and drift under the influence of an external electric field. Cases of the electric field being uniform and non-uniform are investigated separately. A two step/temperature analytical model is proposed to describe the electron as well as phonon temperature profiles and solved using the finite difference method (FDM). The FDM results are compared with the MC results and found to be in good agreement.

Highlights

Electrons and phonons are the thermal energy carriers in solids in general [1]
Very much less attention was given to the lattice thermal conductivity, or the thermal conductivity governed by phonons, since in metals, it is generally believed that phonon contribution to thermal conductivity is negligible compared to the electronic counterpart
Thermal conduction is dominated by phonons in semiconductors; the impact of electron–phonon interaction (EPI) on phonon transport receives less attention due to relatively low carrier concentrations which limits the scattering of phonons by electrons much less important than the phonon–phonon scattering

Summary

Introduction

Electrons and phonons are the thermal energy carriers in solids in general [1]. While electrons have a dominant contribution to the thermal conductivity in metals, phonons play the major role in semiconductors and insulators. Some recent works on the electrothermal properties simulation and modeling on GaN HEMTs are the following: Mei wu et al [8] proposed an electric method for the estimation of temperature in the AlGaN/GaN HEMT channel and they built a 2D electrothermal model to describe the findings; Bikramjith chatterjee et al [9] examined the self heating effects on HEMTs using UV thermoreflectance imaging; Luoyun Yang et al [10] studied the electrothermal mechanism of GaN HEMT and proposed a two-dimensional analytic model for the device; Yu-Chao Hua et al [11] investigated ballistic-diffusive regime thermal spreading resistance in GaN HEMTs; and Qing Hao et al [12] used a coupled electron–phonon MC to investigate temperature distribution in GaN HEMT more accurately. Our MC simulation is aimed to verify the accuracy of the newly developed parabolic two step model for dealing with localized electron source driven thermal transport under the external electric field

Electron–Phonon Monte Carlo Method

Phonon Monte Carlo

Electron Monte Carlo

Numerical Scheme

Results and Discussion

Conclusions