Layers of Be-doped GaN were grown onto Si(111) by means of molecular-beam epitaxy. The relative Be concentration was measured by using secondary-ion mass spectroscopy. The photoluminescence spectra were obtained under continuous wave and time-resolved conditions. A new emission at 3.384eV, which was thought to be related to substitutional Be, was reported; together with its first and second order phonon replica. Clear blue-shifts were observed upon increasing the temperature and excitation power, thus suggesting that this emission was associated with a transition from a residual donor to the Be acceptor. On the basis of time-resolved spectra, of a very slow and strongly non-exponential decay, and of a red-shift of the peak energy position with time, it was confirmed that the Be-related emission had a donor-acceptor character. The estimated ionization energy of the acceptor was about 0.09eV. Therefore, Be was the shallowest p-dopant so far found in GaN.

Experimental evidence for a Be shallow acceptor in GaN grown on Si(111) by molecular beam epitaxy F.J.Sánchez, F.Calle, M.A.Sánchez-García, E.Calleja, E.Muñoz, C.H.Molloy, D.J.Somerford, J.J.Serrano, J.M.Blanco: Semiconductor Science and Technology, 1998, 13[10], 1130-3