(Left) Temperature profile in AlGaN/GaN HFET on sapphire substrate powered at 3.3 W mm-1 without the heat spreader. The maximum temperature is T=181 °C (Right) Temperature profile in an identical AlGaN/GaN HFET on sapphire substrate powered at 3.3 W mm-1 with the graphene – graphite heat spreader. The maximum temperature is T=113 °C. The stronger effect produced by adding the graphene quilt is explained by the much lower thermal conductivity of sapphire. The HFET dimensions and layered structure were kept the same in all simulations. The units used in the figures are (m×10-4). The room temperature is assumed to be 25 °C
Source:
Zhong Yan, Guanxiong Liu, Javed M. Khan & Alexander A. Balandin, Graphene quilts for thermal management of high-power GaN transistors, Nature Communication, 3, 827, 2012
