Thermal conductivity of wurtzite Aluminum Nitride under external electric field

Ultra-wide bandgap (UWBG) semiconductors host the large critical electric fields necessary to support a leap in the power density of next-generation power and radio-frequency electronics. However, effective thermal management of the heat flux incited by high-voltage operation remains a limiting challenge. The current understanding of thermal transport in UWBG semiconductors neglects the departure from equilibrium driven by electric field ( \({E})\) , which becomes more severe at higher power density. In this work, we develop a new computational workflow to obtain non-equilibrium ab initio thermal transport properties under \({E}\) within the density-functional theory - non-equilibrium Green’s function (DFT-NEGF) framework. The predicted cross-plane thermal conductivity ( k ⊥ ) of wurtzite Aluminum Nitride (AlN) is modified by a cross-plane electric field ( \({{E}}z\) ), where the change in k ⊥ depends on the direction of \({{E}}z\) with respect to the polarity of the AlN thin film. The findings provide critical insights to understand thermal transport in devices under operating conditions and design effective thermal management for high-power electronics.