Development of GaN-HEMT using a diamond substrate as a heat spreader

Abstract

GaN-on-diamond high electron mobility transistors (GoD HEMTs) were fabricated by surface-activated room-temperature bonding. A monocrystalline diamond substrate and polycrystalline diamond substrate were finely polished using mechanical polishing techniques and novel polishing techniques utilizing catalytic reactions, respectively. GaN-HEMTs removed from a Si substrate were bonded to the finely-polished diamond substrates. A cross-sectional transmission electron microscope (TEM) image showed that the GaN-HEMTs and diamond substrate were well-bonded with a few-nm-thick interface layer. Measured drain current (I_d) - drain voltage (V_d) curves implied that GaN-HEMTs were successfully transferred on the diamond substrate and HEMT performance was improved due to effective heat dissipation via the diamond with high thermal conductivity. Two-dimensional temperature mapping measurements revealed that fabricated GoD-HEMTs had very improved heat dissipation performance.