Radiation-induced effects in GaN by photoconductivity analysis

Spectral photoconductivity is a very efficient tool to explore the forbidden gap of wide gap semiconduc-tors, detecting band-to-band or deep level-to-band transitions of the charge carriers. In this paper we present some results obtained by spectral photoconductivity concerning HVPE (hy-dride vapour phase epitaxy) grown gallium nitride submitted to high energy proton irradiation. The behav-iour of the material before and after irradiation may give information on the characteristics of the deep bands and their association to surface or bulk defects. In particular we observed how irradiation quenches the yellow band and correspondingly inhibits persistent photocurrent effects. Persistent photocurrent measurements carried out at different temperatures give further insights on the radiation-induced effects. The possible correlation among the deep-related transitions and the persistent photo-effects is here pro-posed.