Molecular-beam epitaxy of p-type m-plane GaN

We report on the plasma-assisted molecular-beam epitaxy of Mg-doped (101¯0) GaN on (101¯0) 6H–SiC. Secondary ion mass spectroscopy measurements show the incorporation of Mg into the GaN films with an enhanced Mg incorporation under N-rich conditions relative to Ga-rich growth. Transport measurements of Mg-doped layers grown under Ga-rich conditions show hole concentrations in the range of p=1×1018 to p=7×1018cm−3 and a dependence between hole concentration and Mg beam equivalent pressure. An anisotropy in in-plane hole mobilities was observed, with the hole mobility parallel to [112¯0] being higher than that parallel to [0001] for the same hole concentration. Mobilities parallel to [112¯0] were as high as ∼11.5cm2∕Vs (at p∼1.8×1018cm−3).