Role of potential barriers in epitaxial layers of semi-insulating GaN layers

The electrical properties of semi-insulating GaN were investigated by dc and microwave techniques. The different epitaxial GaN layers were grown by Metal Organic Chemical Vapour Deposition on a Al2O3 (0001) substrate. Space charge effects along and perpendicular to the direction of layer growth were proposed to explain the observed peculiarities of the dark current and photocurrent. From the temporal and temperature dependences of characteristic time constants in the photoconductivity decay, the details of non-equilibrium states were analysed in the semi-insulating GaN. The well-resolved alpha-particle spectra obtained demonstrates the promise of semi-insulating GaN for ionising radiation detection.