Heat transfer enhancement of N-Ga-Al semiconductors heterogeneous interfaces

Abstract

Heat transfer enhancement of N-Ga-Al semiconductor heterostructure interfaces is critical for the heat dissipation in GaN-based electronic devices, while the effect of the Al_xGa_(1-x)N transition layer component concentration and thickness on the heat transfer mechanism at the GaN-AlN interface is unclear. In this paper, using molecular dynamics simulations based on machine learning potentials, the interfacial thermal conductance (ITC) between GaN-Al_xGa_(1-x)N, AlN-Al_xGa_(1-x)N and GaN-Al_xGa_(1-x)N-AlN heterostructure interfaces are calculated for different transition layer thicknesses with different concentrations of Al fractions, and the reasons for the change of ITC and its heat transfer mechanism were explained by the phonon density of states and the spectral heat current. GaN-AlN heterostructure ITC at 300 K is calculated to be 557 MW/(m²K), and the ITCs of GaN-Al_0.5Ga_0.5 N and AlN-Al_0.5Ga_0.5 N are improved by 128 % and 229 % compared to GaN-AlN, whereas the ITCs of GaN-Al_0.7Ga_0.3N-AlN containing a 0.5 nm transition layer improved by 27.6 %. This is because elemental doping enhances phonon scattering near the interface thereby promoting phonon energy redistribution, but the bulk thermal resistance of the Al_xGa_(1-x)N layer also increases rapidly with increasing doping ratio, and ITC is affected by a combination of these two factors. This work aims to understand the mechanism of transition layer component concentration and thickness on the heat transfer at the GaN-AlN contact interface, which provides a useful guide for better thermal design of the GaN-AlN heterostructure interface.