Comparison of the AlxGa1–xN/GaN Heterostructures Grown on Silicon-on-Insulator and Bulk-Silicon Substrates

Compared with bulk-Si wafer, Al
_x
Ga
_1-x
N/gallium nitride (GaN) heterostructures grown on a 150-mm silicon-on-insulator (SOI) substrate with a 35-nm-thick Si overlayer are shown to have ~50% less wafer bowing. As a result, the 2-D electron gas mobility and the sheet-resistivity uniformity on SOI are improved due to a lower defect density. In terms of device performance, high-electron-mobility transistors (HEMTs) fabricated on the Al
_x
Ga
_1-x
N/GaN-on-SOI exhibit ~20.5% higher saturation drain current as compared with the bulk-Si counterparts. However, due to the poorer conductivity of the buried oxide layer, the Al
_x
Ga
_1-x
N/GaN-on-SOI HEMT suffers greater self-heating, with ~50 K higher channel temperature. With mitigation of self-heating, the Al
_x
Ga
_1-x
N/GaN-on-SOI, in view of its more superior structural and thermal stability, should offer an attractive alternative for integration of the GaN technology with the Si CMOS platform.