GaN-on-Diamond HEMTs with 11W/mm Output Power at 10GHz

Abstract

A new device-first low-temperature bonded gallium nitride (GaN)-on-diamond high-electronic mobility transistor (HEMT) technology with state-of-the-art, radio frequency (RF) power performance is described. In this process, the devices were first fabricated on a GaN-on-silicon carbide (SiC) epitaxial wafer and were subsequently separated from the SiC and bonded onto a high-thermal-conductivity diamond substrate. Thermal measurements showed that the GaN-on-diamond devices maintained equivalent or lower junction temperatures than their GaN-on-SiC counterparts while delivering more than three-times higher RF power within the same active area. Such results demonstrate that the GaN device transfer process is capable of preserving intrinsic transistor electrical performance while taking advantage of the excellent thermal properties of diamond substrates. Preliminary step-stress and room-temperature, steady-state life testing shows that the low-temperature bonded GaN-on-diamond device has no inherently reliability limiting factor. GaN-on-diamond is ideally suited to wideband electronic warfare (EW) power amplifiers as they are the most thermally challenging due to continuous wave (CW) operation and the reduced power-added efficiency obtained with ultra-wide bandwidth circuit implementations.

Prospects for Gallium Nitride-on-Diamond Transistors

“…or comparison with the device. The use of a diamond substrate clearly demonstrates improved heat extraction despite 3X higher dissipated power within the same active area [10]. Fig.…”

“…Fig. 6 shows constant power (CW) load-pull measurements performed on a 12×50μm GaN-on-Diamond device at 10GHz produced 11.0W/mm at a 40V drain bias with 51% PAE [10]. This is the first reported GaN-on-Diamond device result utilizing SOA GaN epitaxy from SiC substrates.…”

“…This bow must be carefully managed to facilitate wafer scale processing. Several groups, including NJTT Program performers Raytheon and Qorvo (RFMD/ Triquint), along with AFRL have demonstrated that the diamond integration process did not significantly degrade the electrical performance and clear trends show improved thermal performance utilizing variants of this diamond integration approach [4][5][6][7][8][9][10][11][12][13]. Process flow for wafer bonding GaN device layers to a free-standing polycrystalline diamond substrate [10].…”

“…GaN power amplifiers are rapidly becoming the technology of choice for a variety of military radar, electronic warfare and communication systems as well as commercial wireless infrastructure components. Significant advances in epitaxial growth, device fabrication and design have enhanced the electrical performance to a point where thermal management is now a primary limiting factor in device and circuit operation [10]. Fig.…”

Поверхностный Тепловой Интерфейс Для Мощных Арсенид-Галлиевых Гетероструктурных Полевых Транзисторов

“…Существует много способов улучшения традиционного теплоотвода, например, [4], но, как отмечалось выше, все они по сути дела связаны с уменьшением толщины подложки. Некоторые варианты таких конструкций [5][6][7] успешно используются в нитрид-галлиевых полевых транзисторах, где из-за высокой удельной выходной СВЧ-мощности хороший отвод тепла особенно важен. Для мощных арсенидгаллиевых НЕМТ-транзисторов применение подобных способов отвода тепла связано с введением дополнительных технологических операций, что вызывает проблемы, всегда сопутствующие изменениям конструкции и технологии изготовления прибора.…”