4-inch GaN HEMT Epiwafers with less Wafer Bow

摘要

Feasibility study to reduce the bow of large diameter GaN HEMT epiwafers on sapphire substrates was performed. The warp of 4-inch GaN HEMT epiwafer including coalescence-promoted buffer layer by IMOVPE was reduced to no more than 22.7 Jim. Despite the thin buffer layers, high electron mobility of 1,457 cm~2/Vs and 436.1 Ohm/sq. sheet resistance was achieved in the developed sample. Prevention of facet formation at the initial stage of the buffer process by applying high temperature coalescence-promoted growth is responsible for the decent electrical characteristics.