Effects of Plasma Processes on the Characteristics of Optical Device Structures Based on GaAs

Abstract

We investigate the effects of inductively coupled O2 plasma ashing, capacitively coupled C3F8 plasma etching, and capacitively coupled C3F8/O2 plasma etching on the optical and electrical characteristics of GaAs-related optical device structures. The O2 plasma ashing produces non radiative recombination centers close to the sample surface. The sample with a cap AlGaAs layer prevents the degradation of photoluminescence (PL) intensity, probably inhibiting the penetration of damaging ions into the buried quantum well. The C3F8 plasma etching also degrades the PL intensity; however, under moderate conditions, the effect of non radiative surface recombination can be suppressed by the formation of a surface oxide layer. On the other hand, the formation of oxide increases the specific contact resistance (ρc) of the electrode. The etching with C3F8/O2 mixed plasma also deteriorates the optical characteristics presumably owing to the synthesized impact of the constituent gases, while it has limited effect on ρc.