Study of low-frequency noise in GaN-on-Si films obtained by laser-assisted debonding

Detailed optical and electronic characterizations were conducted on interdigitated devices fabricated on both GaN-on-sapphire and GaN-on-Si films. The GaN-on-Si films, up to dimension of 1 cm by 1 cm, were obtained by layer transfer of laser-debonded hydride vapor phase epitaxy (HVPE)-grown GaN films deposited on sapphire substrates. The study of breakdown voltages and the leakage currents show comparable results for both types of devices indicating the integrity of the devices did not suffer due to the liftoff process. A reduction in the yellow emission is observed in the debonded GaN layer suggesting an improvement in the material quality. To investigate the physical origin of this, low-frequency noise was examined on both Schottky and ohmic junctions fabricated on both types of materials. The experimental data on low-frequency noise indicated significant reduction in the defect density in the debonded film. This is believed to arise from a thermal annealing effect during the laser illumination process.