p-type conduction in as-grown Mg-doped GaN grown by metalorganic chemical vapor deposition

We have clarified the effect of H-2 and NH3 on the passivation of Mg acceptor in p-type GaN films grown by metalorganic chemical vapor deposition. It has been found that the small amount of H-2 carrier gas strongly influences the electrical property of the Mg-doped GaN films. Low-resistivity p-type GaN has been obtained by H-2-free growth without any post-treatments. Its acceptor concentration is as high as that obtained by conventional H-2-rich growth with subsequent thermal annealing. It has also been clarified that hydrogen produced by NH3 dissociation does not prevent Mg from electrically activating in H-2-free growth. (C) 1998 American Institute of Physics. [S0003-6951(98)02714-4].