Growth of p-type and n-type m-plane GaN by molecular beam epitaxy

Plasma-assisted molecular beam epitaxial growth of Mg-doped, p-type and Si-doped, n-type m-plane GaN on 6H m-plane SiC is demonstrated. Phase-pure, m-plane GaN films exhibiting a large anisotropy in film mosaic (∼0.2° full width at half maximum, x-ray rocking curve scan taken parallel to [112¯0] versus ∼2° parallel to [0001]) were grown on m-plane SiC substrates. Maximum hole concentrations of ∼7×1018cm−3 were achieved with p-type conductivities as high as ∼5Ω−1cm−1 without the presence of Mg-rich inclusions or inversion domains as viewed by cross-section transmission electron microscopy. Temperature dependent Hall effect measurements indicate that the Mg-related acceptor state in m-plane GaN is the same as that exhibited in c-plane GaN. Free electron concentrations as high as ∼4×1018cm−3 were measured in the Si-doped m-plane GaN with corresponding mobilities of ∼500cm2∕Vs measured parallel to the [112¯0] direction.