A novel strategy for GaN-on-diamond device with a high thermal boundary conductance

To achieve high device performance and high reliability for the gallium nitride (GaN)-based high electron mobility transistors (HEMTs), efficient heat dissipation is important but remains challenging. Enormous efforts have been made to transfer a GaN device layer onto a diamond substrate with a high thermal conductivity by bonding. In this work, two GaN-diamond bonded composites are prepared via modified surface activated bonding (SAB) at room temperature with silicon interlayers of different thicknesses (15 nm and 22 nm). Before and after post annealing process at 800 degrees C, thermal boundary conductance (TBC) across the bonded interface including the interlayer and the stress of GaN layer are investigated by time domain thermoreflectance and Raman spectroscopy, respectively. In the case of as-bonded samples, TBC of the 15 nm Si interlayer (32.4 MW/m(2)-K) was higher than that of the 22 nm (28.0 MW/m(2)-K); but after annealing, TBC of the 15 nm Si interlayer (71.3 MW/m(2)-K) became lower than that of the 22 nm (85.9 MW/ m(2)-K), because the annealing is especially effective for thicker interlayer to improved interfacial TBC. The obtained stress was less than 230 MPa for both before and after the annealing, and this high thermal stability indicates that the room-temperature bonding can realize a GaN-on-diamond template suitable for further epitaxial growth or device process. (C) 2022 Published by Elsevier B.V.

为了使基于氮化镓（GaN）的高电子迁移率晶体管（HEMTs）实现高性能和高可靠性，高效散热至关重要，但仍然具有挑战性。人们已经付出了巨大努力，通过键合将GaN器件层转移到具有高导热性的金刚石衬底上。在这项工作中，通过改进的室温表面活化键合（SAB）技术，使用不同厚度（15纳米和22纳米）的硅中间层制备了两种GaN - 金刚石键合复合材料。在800℃退火前后，分别通过时域热反射和拉曼光谱研究了键合界面（包括中间层）的热边界电导（TBC）以及GaN层的应力。对于键合后的样品，15纳米硅中间层的TBC（32.4 MW/m²·K）高于22纳米的（28.0 MW/m²·K）；但退火后，15纳米硅中间层的TBC（71.3 MW/m²·K）低于22纳米的（85.9 MW/m²·K），因为退火对较厚的中间层提高界面TBC特别有效。退火前后所测得的应力均小于230 MPa，这种高热稳定性表明室温键合可以实现适用于进一步外延生长或器件工艺的GaN - 金刚石模板。（C）2022年由爱思唯尔B.V.出版