Thermal Design Rules of AlGaN/GaN-Based Microwave Transistors on Diamond

Autor: James W Pomeroy, Jim Carroll, Feiyuan Yang, Martin Kuball, Thomas Gerrer, Daniel Francis, Marty Yarborough, Larry Witkowski, Michael J. Uren, Brian Loran
Rok vydání: 2021
Předmět:
Zdroj: IEEE Transactions on Electron Devices. 68:1530-1536
ISSN: 1557-9646
0018-9383
Popis: Reliable operation of high power GaN amplifiers at maximum performance relies on the mutual optimization of several design parameters constrained by a defined thermal budget. On high thermal conductivity, substrates, such as SiC and diamond, undergo small changes within the design that can lead to drastic changes in channel temperature. We utilize finite element simulations to provide design rules for device structures for GaN-on-diamond amplifiers, benchmarked against GaN-on-SiC. At 8 W/mm power density, a $13~\mu \text{m}$ gate pitch GaN-on-diamond design compared to a commonly employed $40~\mu \text{m}$ gate pitch GaN-on-SiC design results in ~40 °C and ~20 °C cooler peak channel temperature, i.e., 182 °C for single and 201 °C for polycrystalline diamond (PCD) substrates despite the $3\times $ larger areal power density. The simulations were validated with 1.25 mm wide, 10-finger GaN-on-diamond high-electron-mobility transistors (HEMT) devices of 13 and $40~\mu \text{m}$ gate pitch, with good electrical performance in pulsed ${I}$ – ${V}$ measurements and Raman thermography measurements. The commonly used Au-Sn die-attach is determined as the next limiting factor for GaN-on-Diamond technologies which require the development of new die-attach materials.
Databáze: OpenAIRE