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Detailed spectrometry and optical spectroscopy studies carried out on GaN crystals grown in solution detect and identify Mg as the dominant shallow acceptor. Selective etching of crystals with higher Mg levels than that of the donor concentration background indicates that Mg acceptors incorporate preferentially in the N-polar face. Electrical transport measurements verified an efficient incorporation and activation of the Mg acceptors. These results suggest that this growth method has the potential to produce p-type doped epitaxial layers or p-type substrates characterized by high hole concentration and low defect density.

Epitaxial GaN films were grown by metal organic chemical vapor deposition (MOCVD) on functionalized epitaxial graphene (EG) using a thin (~11 nm) conformal AlN nucleation layer. Raman measurements show a graphene 2D peak at 2719 cm-1 after GaN growth. X-ray diffraction analysis reveals [0001]-oriented hexagonal GaN with (0002) peak rocking curve full width at the half maximum (FWHM) of 544 arcsec. The FWHM values are similar to reported values for GaN grown by MOCVD on sapphire. The GaN layer has a strong room-temperature photoluminescence band edge emission. Successful demonstration of GaN growth on EG opens up the possibility of III–nitride/graphene heterostructure-based electronic devices and promises improved performance.