Interface thermal conductance between β-Ga2O3 and different substrates

The ultra-large bandgap semiconductor, β-Ga2O3, has shown great potential in application of power electronics with capabilities beyond existing materials. However, due to its ultra-low thermal conductivity, interface thermal conductance (ITC) between β-Ga2O3 and substrate becomes one of the key points to facilitate heat dissipation of devices. In this paper, the ITC between β-Ga2O3 and different substrates (SiO2, 4 H-SiC, α-Al2O3 and Si) is investigated through combing of Landauer formula with the acoustic mismatch model (AMM) and diffusive mismatch model (DMM). It is found that Ga2O3/Si interface has the largest ITC of 1.01 GW m−2 K−1 (0.47 GW m−2 K−1) by AMM (DMM) at 300 K, and Ga2O3/SiO2 interface has the smallest ITC of 0.54 GW m−2 K−1 (0.23 GW m−2 K−1) by AMM (DMM) at 300 K. In between, the ITC of Ga2O3/Al2O3 interface is larger than that of Ga2O3/SiC interface. Regardless of the difference in absolute values of ITCs, the rule for the relative magnitudes of ITCs for the four interfaces is the same for AMM and DMM predictions. The underlying physical mechanism for the difference in ITC of different interfaces is clarified by phonon transmission function and mismatches of impedance and phonon density of states. The study can provide guidance for thermal management and is of great importance for the design of β-Ga2O3 based device.