Blue emission in Mg doped GaN studied by time resolved spectroscopy

A strong blue emission is present when GaN films are heavily doped with Mg. It is known that compensation by non-intended donors reduces the free hole density at least two orders of magnitude when compared with the Mg concentration. Previous work on the blue band in heavily Mg doped (10(20) cm(-3)) material shows that two main emissions contribute to the band. The dependence on excitation intensity shows a shift of the peak position of the emissions too large to be attributed to donor acceptor pair (DAP) recombination. In the present work we analyse by time resolved spectroscopy, in conditions of low excitation density, the temperature dependence of the blue emission and compare it with steady state data. From the data a model for this emission is proposed.