Influence of the Metal–Semiconductor Interface Model on Power Conservation Principle in a Simulation of Bipolar Devices

Janusz Wozny,Zbigniew Lisik,Jacek Podgorski

doi:10.3390/electronics10243120

Abstract

The purpose of the study is to present a proper approach that ensures the energy conservation principle during electrothermal simulations of bipolar devices. The simulations are done using Sentaurus TCAD software from Synopsys. We focus on the drift-diffusion model that is still widely used for power device simulations. We show that without a properly designed contact(metal)–semiconductor interface, the energy conservation is not obeyed when bipolar devices are considered. This should not be accepted for power semiconductor structures, where thermal design issues are the most important. The correct model of the interface is achieved by proper doping and mesh of the contact-semiconductor region or by applying a dedicated model. The discussion is illustrated by simulation results obtained for the GaN p–n structure; additionally, Si and SiC structures are also presented. The results are also supported by a theoretical analysis of interface physics.

Highlights

The proper design of power semiconductor devices is a real need of high-reliability electronics
Analyzing several other publications devoted to bipolar structures such as diodes, [9,10,11,12], IGBTs [13], Peltier modules [14], heterojunction bipolar transistors (HBTs) [15], we find that this problem is not tackled
The difference in power characteristics between SiC and GaN for the S1 structure (Figure 6a,c) is caused by the opposite type of electrothermal feedback resulting from a different set of material parameters, energy band gap model, mobility model, and thermoelectric models

Summary

Introduction

The proper design of power semiconductor devices is a real need of high-reliability electronics. Since power devices must be large to sustain high current densities, the drift-diffusion model is still appropriate for modeling the device structure. We would like to focus on Synopsys Sentaurus TCADTM software [2]. This software program is widely used for semiconductor devices simulation. Sentaurus TCADTM offers a vast set of physical models to analyze semiconductor structures. We use the thermodynamic model [2], which is based on Wachutka’s work [6,7] This model is an extension of the drift-diffusion approach with a rigorous treatment of heat transport and electrothermal effects present in semiconductors. We do not want to judge if the reported results are fully correct, since there are no models details reported and it is not possible to confirm if all the results are fully validated

Objectives

Results

Conclusion