The use of TLM contact resistance measurements in assessing ICP-RIE and RIE induced damage on GaN structures

We report on the use of TLM contact resistivity measurements to assess plasma induced damage in GaN based structures. Two methods of etch processing were used, reactive ion etching (RIE) and inductively coupled plasma reactive ion etching (ICP-RIE). Etches were carried out on n-type Gallium Nitride and a comparison of contact resistivity as a function of rf power input (ion energy) was carried out to assess the damage induced during etching. The GaN etch rate showed a linear dependence on dc-bias for both RIE and ICP processing with a maximum of 100 nm/min. for RIE and 900 nm/min. for ICP.