Cheng Zhe, Mu Fengwen, Yates Luke, Suga Tadatomo, Graham Samuel
George W. Woodruff School of Mechanical Engineering , Georgia Institute of Technology , Atlanta , Georgia 30332 , United States.
Collaborative Research Center , Meisei University , Hino-shi , Tokyo 191-8506 , Japan.
ACS Appl Mater Interfaces. 2020 Feb 19;12(7):8376-8384. doi: 10.1021/acsami.9b16959. Epub 2020 Feb 10.
The wide bandgap, high-breakdown electric field, and high carrier mobility makes GaN an ideal material for high-power and high-frequency electronics applications, such as wireless communication and radar systems. However, the performance and reliability of GaN-based high-electron-mobility transistors (HEMTs) are limited by the high channel temperature induced by Joule heating in the device channel. Integration of GaN with high thermal conductivity substrates can improve the heat extraction from GaN-based HEMTs and lower the operating temperature of the device. However, heterogeneous integration of GaN with diamond substrates presents technical challenges to maximize the heat dissipation potential brought by the ultrahigh thermal conductivity of diamond substrates. In this work, two modified room-temperature surface-activated bonding (SAB) techniques are used to bond GaN and single-crystal diamond. Time-domain thermoreflectance (TDTR) is used to measure the thermal properties from room temperature to 480 K. A relatively large thermal boundary conductance (TBC) of the GaN/diamond interfaces with a ∼4 nm interlayer (∼90 MW/(m K)) was observed and material characterization was performed to link the interfacial structure with the TBC. Device modeling shows that the measured TBC of the bonded GaN/diamond interfaces can enable high-power GaN devices by taking full advantage of the ultrahigh thermal conductivity of single-crystal diamond. For the modeled devices, the power density of GaN-on-diamond can reach values ∼2.5 times higher than that of GaN-on-SiC and ∼5.4 times higher than that of GaN-on-Si with a maximum device temperature of 250 °C. Our work sheds light on the potential for room-temperature heterogeneous integration of semiconductors with diamond for applications of electronics cooling, especially for GaN-on-diamond devices.
宽带隙、高击穿电场和高载流子迁移率使氮化镓成为用于高功率和高频电子应用（如无线通信和雷达系统）的理想材料。然而，基于氮化镓的高电子迁移率晶体管（HEMT）的性能和可靠性受到器件沟道中焦耳热引起的高沟道温度的限制。将氮化镓与高导热率衬底集成可以改善基于氮化镓的HEMT的散热，并降低器件的工作温度。然而，氮化镓与金刚石衬底的异质集成在最大化金刚石衬底的超高导热率所带来的散热潜力方面面临技术挑战。在这项工作中，采用了两种改进的室温表面活化键合（SAB）技术来键合氮化镓和单晶金刚石。利用时域热反射（TDTR）来测量从室温到480 K的热性能。观察到具有约4 nm中间层的氮化镓/金刚石界面具有相对较大的热边界电导（TBC）（约90 MW/(m·K)），并进行了材料表征以将界面结构与TBC联系起来。器件建模表明，所测量的键合氮化镓/金刚石界面的TBC能够通过充分利用单晶金刚石的超高导热率来实现高功率氮化镓器件。对于建模器件，金刚石上氮化镓的功率密度可比碳化硅上氮化镓的值高约2.5倍，比硅上氮化镓的值高约5.4倍，器件最高温度为250°C。我们的工作揭示了半导体与金刚石进行室温异质集成在电子冷却应用中的潜力，特别是对于金刚石上氮化镓器件。
