Thermal conductivity of bulk GaN grown by HVPE: Effect of Si doping

Abstract

The thermal conductivity of bulk GaN grown by Hydride Phase Vapor Epitaxy with intentional Si doping was measured using the 3ω method. The effect of Si concentration ranging from 1.6 × 1016 to 7 × 1018 cm−3 on the thermal conductivity was studied over the temperature range of 295–470 K. The room temperature thermal conductivity was found to decrease with increasing Si doping from 245 to 210 W/m · K. Also, for each Si doped sample the thermal conductivity decreases with increasing temperature. The experimental data were analysed by a modified Callaway model and the contribution of different resistive phonon scattering process was examined. It was found that in n‐type GaN the phonon‐free‐electron scattering became an important resistive process that leads to a reduction of the thermal conductivity at high temperatures. At the highest free electron concentrations, electronic thermal conduction was found to play a role in addition to lattice thermal conduction and compete with the effects of phonon‐free‐electron scattering.

Anisotropic thermal conductivity of AlGaN/GaN superlattices

“…Even though the thermal conductivity of bulk and film GaN was extensively investigated over the last decades [12][13][14][15][16][17][18], there were only several reports on thermal conductivity of AlGaN films and AlN/GaN superlattices. Results of the measurements of Al x Ga 1−x N films (with x changing from 0.1 to 0.44) showed that thermal conductivity decreases with increasing amount of Al mass fraction and decreasing film thickness [19][20][21][22][23][24].…”

Matryoshka phonon twinning in α-GaN

“…For example, existing experimental measurements of the phonon dispersion relation of -GaN are limited to ambient conditions, and the phonon scattering processes and the temperature effects are mostly unexplored [9,10]. Moreover, the anisotropic thermal transport of -GaN along a (inplane) and c (out-of-plane) axis directions remains controversial due to the challenges in transport measurements [7,[11][12][13][14][15][16][17][18] and calculations [19][20][21]. Therefore, a more comprehensive understanding of the phonon dynamics is pivotal to investigating the thermal transport and other thermodynamics properties of GaN.…”

Hybrid Electrothermal Simulation of a 3-D Fin-Shaped Field-Effect Transistor Based on GaN Nanowires

“…For GaN doped with Si, phonon scattering by free electrons should be further considered and can reduce the room-temperature thermal conductivity by ~13% at a doping level of 7.0×10 18 cm -3 . 16 This new phonon-scattering mechanism is further considered for heavily doped GaN nanowires and the scattering rate is given as 12 ( ) 2 *3 1 4 * 2 * 2 2 2 * 2 * 2 2 2 * 2 1 4 2…”