Novel all-around diamond integration with GaN HEMTs demonstrating highly efficient device cooling

Abstract

A novel all-around heat spreader for Nitrogenpolar GaN HEMTs is implemented by integrating it with CVD grown polycrystalline (PC) diamond to facilitate hot spot removal at the device level which is often a source of premature breakdown. Nearly isotropic diamond growth enabled a high in-plane thermal conductivity (TC). Using a temperature dependent gate resistance method, devices with 500 nm thick all-around diamond, exhibited 98 ± 19 °C (measured on multiple devices over the wafer) lower gate electrode temperature at 9.5 W/mm DC power compared to the control devices without diamond. The diamond integration did not lead to any degradation in the dispersion behavior. Furthermore, thermo-reflectance imaging and IV thermometry were used to characterize the thermal behavior of all-around diamond heat spreader which validated gate resistance method results showing similar temperature reduction in channel compared to control sample.