Process defect studies in dry-etch recessed gate AlGaN/GaN HEMTs

We have investigated recess induced defects by comparing Schottky contacts on unintenionally doped GaN and AlGaN samples prepared by different dry-etching methods at different bias voltages and ion incidence angles. The backward current of the current-voltage characteristics indicates the effect of physical damage of the semiconductor surface. We have found a lower backward current by using an ion beam etching (IBE) process in contrast to an electron cyclotron resonance reactive ion etching (ECR-RIE) process which is used usually for low damage dry-etching of GaN. With one of this IBE processes recessed HEMTs were fabricated on AlGaN/GaN heterostructures grown by low pressure MOVPE and compared to HEMTs without recess.