Reduced Self-Heating in AlGaN/GaN HEMTs Using Nanocrystalline Diamond Heat-Spreading Films

Nanocrystalline diamond (NCD) thin films are deposited as a heat-spreading capping layer on AlGaN/GaN HEMT devices. Compared to a control sample, the NCD-capped HEMTs exhibited approximately 20% lower device temperature from 0.5 to 9 W/mm dc power device operation. Temperature measurements were performed by Raman thermography and verified by solving the 2-D heat equation within the device structure. NCD-capped HEMTs exhibited 1) improved carrier density N(S), sheet resistance R(SH); 2) stable Hall mobility mu(H) and threshold voltage V(T); and 3) degraded on-state resistance R(ON), contact resistance R(C), transconductance G(m), and breakdown voltage V(BR).