Selective Area Mass Transport Regrowth of Gallium Nitride

Selective area mass transport regrowth of GaN was performed on wafers with etched wells and SiO2 mask. The samples were annealed in NH3 and H2 flow, with no gallium precursor. At 1060°C, only little mass transport occured, but the sidewall morphology changed, depending on crystallographic orientation. At 1160°C, the sidewalls grew out about 1 µm in 1 min, independent of orientation. The technique can potentially be performed in an annealing chamber, providing a low cost regrowth process. A promising application is ohmic contact regrowth to high composition AlGaN/GaN high electron mobility transistors.