Talk abstract

The transport properties of Mg doped, p-type GaN films grown by MOCVD have been measured using Hall effect and resistivity measurements over a temperature range from 400 - 50K. The mobility is found to increase slowly over the temperature range from 400 to 200K. Below this temperature the mobility is seen to decrease rapidly, while the corresponding Hall carrier density goes through a minimum before increasing to lower temperatures. These results have been analysed, using a two-band model. This incorporates a simple valence band model, calculated using a relaxation time approximation, and additional transport within an acceptor impurity band. A good fit has been obtained self-consistently to both the mobility and carrier density over a temperature range of 400-120K. We find that neutral impurity scattering plays an important role in limiting the hole mobility while the best fits are obtained assuming an acoustic-deformation potential of ~20eV.