Interfacial Thermal Transport in Top-Side Diamond Integrated AlGaN/GaN High Electron Mobility Transistors
At a Glance
Section titled āAt a Glanceā| Metadata | Details |
|---|---|
| Publication Date | 2025-10-20 |
| Journal | ACS Applied Materials & Interfaces |
| Authors | Husam Walwil, Mohamadali Malakoutian, Daniel Shoemaker, Kelly Woo, Rohith Soman |
| Institutions | Pennsylvania State University, Stanford University |
Abstract
Section titled āAbstractāAlGaN/GaN high electron mobility transistors (HEMTs) are critical components in modern radio frequency (RF) power amplifiers. However, commercial AlGaN/GaN HEMTs often require power derating to maintain safe channel temperatures. Deposition of a polycrystalline diamond heat spreader onto an as-fabricated device offers a means to facilitate efficient top-side heat extraction. However, the dielectric interlayer used for the growth of a diamond heat spreader and the AlGaN barrier introduce interfacial thermal resistances that can limit the heat transfer performance of the diamond. In this work, a polycrystalline diamond heat spreader was deposited on an AlGaN/GaN-on-SiC epitaxial wafer using a 9.7 nm SiO<sub>2</sub> interlayer. The total thermal boundary resistance (<i>TBR</i>) including contributions from the SiO<sub>2</sub> layer and the AlGaN barrier was determined as a function of the temperature using time-domain thermoreflectance (TDTR). A <i>TBR</i> of 15.8 Ā± 1.44 m<sup>2</sup>K GW<sup>-1</sup> was measured at room temperature, primarily dominated by the contribution of the SiO<sub>2</sub> interlayer. A notable contribution from the AlGaN barrier was also identified, which is expected to become more significant with further thinning of the interlayer. A slight decrease in the <i>TBR</i> with temperature was observed, consistent with the temperature-dependent increase in the thermal conductivity of the amorphous SiO<sub>2</sub> layer. Thermal modeling of a multifinger AlGaN/GaN HEMT was performed to evaluate the cooling effectiveness of the top-side diamond and provide design guidelines for optimal integration, considering key parameters such as the diamond thermal conductivity, <i>TBR</i>, and film thickness.