Improved GaN materials and devices through confined epitaxy

An approach to reduce vertical threading dislocations in the active regions of III-nitride devices is described. The approach involves confined homo- or heteroepitaxy of GaN materials using sputtered oxide masks to delineate growth regions and conventional metal-organic chemical vapor deposition. The resulting confined epitaxial material is terminated with equilibrium crystal facets, which form hexagonal mesas, and contains a reduced dislocation density and reduced strain compared to the underlying template layer for homoepitaxial growth. Characterization of pn junction diodes grown with this approach reveals significantly reduced leakage currents in as-grown, unpassivated structures (as low as 1×10−7Acm−2).