# Recent Advances in Diamond-Capped GaN HEMTs for RF Application

## TL;DR

Diamond capping improves cooling in GaN transistors for better performance in high-power RF applications.

## Contribution

A review of recent technological advances in integrating diamond capping with GaN HEMTs for thermal management.

## Key findings

- Diamond capping reduces self-heating in GaN HEMTs due to its high thermal conductivity.
- Recent progress includes optimized thermal boundary resistance and process compatibility for diamond-GaN integration.
- Thermal simulations and film growth techniques have enhanced the performance of diamond-capped devices.

## Abstract

Self-heating effects severely limit the performance of gallium nitride high-electron-mobility transistors (GaN HEMTs) in high-power radio frequency (RF) applications. Diamond capping technology leveraging diamond’s exceptional thermal conductivity (>2000 W/m·K) has emerged as a highly promising near-junction cooling solution. However, its integration with GaN HEMTs faces challenges including lattice/thermal mismatch, high thermal boundary resistance (TBR), and process compatibility. This review summarizes recent progress in high-thermal-conductivity diamond film growth, TBR optimization, thermal simulations, and the integrated process with GaN devices. These technological breakthroughs enable diamond-capped GaN HEMTs with an excellent comprehensive performance. Continued advances in these fields will be critical for fully releasing the capabilities of diamond capping technology for GaN HEMTs in high-frequency and high-power applications.