Effect of plasma process on n-GaN surface probed with electrochemical short loop

Abstract

Plasma etching treatments are important steps in GaN-based devices fabrication, but can create defects on GaN surfaces. These surface defects can strongly alter device performances. The main objective of this work is to characterize the impact of different plasma etching recipes using an innovative electrochemical short loop based on Mott-Schottky (MS) method. The effect of defects has been studied in terms of Fermi Level pinning. Barrier height has been identified as a relevant criteria to describe surface damage induced by plasma treatment. Probing Conventional LETI plasma etching process with the Mott-Schottky method demonstrates a good reproducibility of the electrochemical data and confirms the reliability of the developed method. Various electrochemical tests conducted on 3 plasmas recipes demonstrated that: 1) the RIE etching is damaging, 2) the optimized RIE (Steady A) is less damaging than the other RIE (Steady B) and 3) the RIE associated with ALE process shows the least damaging plasma recipe, as expected.