Thermal resistance of GaN/AlN graded interfaces

TL;DR

This study quantifies how compositionally graded GaN/AlN interfaces affect thermal resistance, revealing a complex dependence on interface thickness and similarities to thin-film alloy behavior, which impacts power electronic device design.

Contribution

It provides the first ab initio analysis of thermal resistance in graded GaN/AlN interfaces, highlighting the power-law dependence and effective alloy behavior.

Findings

Thermal resistance increases with interface thickness following a non-trivial power law.

Graded interfaces behave similarly to thin-film alloys at relevant length scales.

Composition grading can influence heat dissipation in power electronics.

Abstract

Compositionally graded interfaces in power electronic devices eliminate dislocations, but they can also decrease thermal conduction, leading to overheating. We quantify the thermal resistances of GaN/AlN graded interfaces of varying thickness using ab initio Green's functions, and compare them with the abrupt interface case. A non-trivial power dependence of the thermal resistance versus interface thickness emerges from the interplay of alloy and mismatch scattering mechanisms. We show that the overall behavior of such graded interfaces is very similar to that of a thin-film of an effective alloy in the length scales relevant to real interfaces.