On the performance of GaN-on-Silicon, Silicon-Carbide, and Diamond substrates

In this article, threading dislocations and its impact on the electrical and thermal performance of GaN-on-Diamond (Dia), -SiC, and -Si high electron mobility transistor (HEMT) has been investigated. TCAD simulation of GaN-HEMT is performed with various buffer traps to mimic the lattice mismatch/dislocation density at GaN/Si, GaN/SiC, and GaN/Dia interface. It has been found that, the dislocations not only induce traps, but also degrade the thermal conductivity of the GaN-buffer. This accordingly could deteriorate the thermal characteristic of GaN-on-Dia, which has higher lattice mismatch with respect to GaN-on-SiC. This investigation showed that the growth process of GaN-on-Dia should be optimized in order to reduce the threading dislocations. This accordingly could dramatically further improve its outstanding thermal characteristics with respect to GaN-on-SiC and GaN-on-Si devices.