Weak effects of electron-phonon interactions on the lattice thermal conductivity of wurtzite GaN with high electron concentrations
J. R. Sun, Shouhang Li, Zhen Tong, Cheng Shao, Xiangchuan Chen, Qianqian Liu, Yucheng Xiong, Meng An, Xiangjun Liu
Abstract
Wurtzite gallium nitride (GaN) has great potential for high-frequency and high-power applications due to its excellent electrical and thermal transport properties. However, enhancing the performance of GaN-based power electronics relies on heavy doping. Previous studies showed that electron-phonon interactions have strong effects on the lattice thermal conductivity of GaN due to the Fr\"ohlich interaction. Surprisingly, our investigation reveals weak effects of electron-phonon interactions on the lattice thermal conductivity of $\mathit{n}$-type GaN at ultrahigh electron concentrations and the impact of the Fr\"ohlich interaction can be ignored. The small phonon-electron scattering rate is attributed to the limited scattering channels, quantified by the Fermi surface nesting function. In contrast, there is a significant reduction in the lattice thermal conductivity of $\mathit{p}$-type GaN at high hole concentrations due to the relatively larger Fermi surface nesting function. Meanwhile, as $\mathit{p}$-type GaN has relatively smaller electron-phonon matrix elements, the reduction in lattice thermal conductivity is still weaker than that observed in $\mathit{p}$-type silicon. Our work provides a deep understanding of thermal transport in doped GaN and the conclusions can be further extended to other wide-band-gap semiconductors, including $\ensuremath{\beta}\ensuremath{-}{\mathrm{Ga}}_{2}{\mathrm{O}}_{3}$, AlN, and ZnO.