Low contact resistance to plasma-etched p-type GaN

Reported is an investigation into the effect of very low plasma power on the electrical characteristics of ohmic contacts to etched p-GaN, by using very low radio frequency (RF) etching power and inductively coupled plasma (ICP) power. The results, assessed by current-voltage (I-V) characteristics and transfer length method analysis, indicate that the ohmic contacts to the etched material were improved significantly by the use of RF/ICP power of 20/40 W. A specific contact resistance as low as 0.035 cm² was obtained for unannealed contacts. This is the lowest value that has been reported so far for contacts to etched p-GaN without the use of regrowth techniques.