Modeling of Self-Heating Effects in GaN/AlGaN Heterostructure Field-Effect Transistors and Device Structure Optimization
Konstantin A. Filippov and Alexander A. Balandin
Nano-Device Laboratory, Electrical Engineering, UCR, US
Keywords: self-heating, GaN, HFET, heterostructure, thermal management
In this paper we present results of our simulation of temperature rise in GaN/AlGaN HFETs characterized by different geometry, layered structure, doping density and substrate type. We do note make simplifying assumptions of the uniform thermal conductivity of the layered structure. Instead, the proposed self-heating simulation uses first-principle model for the GaN thermal conductivity developed in our group . It allowed us to include the effects of thermal conductivity anisotropy due to crystalline structure, dislocation network orientation, Al content in the barrier and the presence of unevenly distributed dopants and defects. The results for temperature rise and mobility degradation were obtained on the basis of solution of the heat diffusion equation for 2D and 3D cases. The applicability of both approaches and numeric errors are discussed. Using developed simulation tools we compare different types of HFETs with respect to their thermal management and performance. It is shown that channel doping in GaN/AlGaN HFETs on SiC substrate may lead to about 13% increase of the maximum temperature in the channel in comparison with the un-doped channel HFETs with higher Al content in the barrier.
1. J. Zou, D. Kotchetkov, A.A. Balandin, et al., J. Appl. Phys., 92, 2534 (2002).
NSTI Nanotech 2003 Conference Technical Program Abstract