Hard Materials Seminar - "Selective Area Growth of GaN Mesas on Nitridated β-Ga2O3 via Plasma-Assisted Molecular Beam Epitaxy"

With a high critical electric field strength and bulk substrate availability, β-Ga₂O₃ is a promising ultrawide-bandgap semiconductor for future power electronics. While it has many advantageous properties, p-type doping remains a challenge. GaN is a mature material for power applications, and its ability to be p-doped, combined with its low lattice mismatch with β-Ga₂O₃, makes it a strong choice for enabling p-n heterojunctions. Previously by our group, nitridation of β-Ga₂O₃ substrates to produce a buffer layer has been explored via an rf-nitrogen plasma, and subsequent epitaxy of GaN via plasma-assisted molecular beam epitaxy (PAMBE) has enabled crystalline GaN and vertical p-n diodes. In this work, selective area growth methods have been implemented and investigated for GaN/Ga₂O₃ heteroepitaxy to enable the formation of GaN mesas while avoiding typical etching-induced damage. It was found that the structural integrity of the growth mask and GaN mesas hold during fabrication and growth. Future work aims to optimize substrate surface roughness during growth-mask fabrication and minimize mask-induced strain through studying Raman spectroscopy.