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
NS
, sheet resistance
R
_SH
; 2) stable Hall mobility μ
H
and threshold voltage
VT
; and 3) degraded on-state resistance
RON
, contact resistance
RC
, transconductance
Gm
, and breakdown voltage
V
_BR
.