Growth of microcrystalline diamond films after fabrication of GaN high-electron-mobility transistors for effective heat dissipation
Junya Yaita, Atsushi Yamada, Junji Kotani
Abstract
Abstract Diamond films were grown on GaN high-electron mobility transistors (HEMTs) to improve thermal dissipation. We observed the temperature reduction in GaN HEMTs using Raman spectroscopy. The large-grain-size (over 1 μ m) diamond films grown under the 〈110〉 preferential growth condition exhibited a high thermal conductivity of over 200 W m −1 K −1 . These diamond films, which were grown at a high temperature of 700 °C, could be directly applied onto the GaN HEMT surface using a thermally stable SiN x metal insulator semiconductor gate structure. The maximum temperature and thermal resistance of the GaN HEMTs decreased by 100 K and from 12.7 mm K W −1 to 7.4 mm K W −1 , respectively, when microcrystalline diamond films were applied onto the HEMT surfaces. As a result, the current density and trans-conductance of the GaN HEMTs were improved after diamond-film growth.