Space charge effects, carrier capture transient behaviour and α particle detection in semi-insulating GaN

The electrical properties of a semi-insulating GaN (SI-GaN) epitaxial layer have been investigated and regimes of space charge and Ohmic currents found. Microwave and dc current modes were used for temporal measurements of the photocurrent. Transient behaviour was observed in the injection current and photo-response, with a wide range of time constants. The role of the space charge has been analysed and a previous columnar model of the epitaxial layer is shown to require modification. The nature of traps and recombination centres is discussed. Some promising data demonstrating the application of this SI-GaN for the detection of ionising particles, specifically α particles, is presented.