Rapid Annealing of Rie-Induced Damage in GaAs and AlGaAs

Abstract

ABSTRACTIon bombardment of the surface during CCI2 F2:O2 or C2 H6:H2 :Ar reactive ion etching of GaAs and AlGaAs can produce a heavily disordered near-surface (∼1000A for 380V self-bias on the cathode in a parallel plate reactor) region. The damage in this layer causes carrier depletion effects due to trapping of deep level defects. We have investigated the in-situ and post-RIE annealing of both the structural disorder and the electrical effects of the damage using TEM, ion channelling, C-V and I-V measurements. Etching at 400°C reduced the RIE-induced damage due to dynamic annealing processes. Carrier reductions of approximately an order of magnitude were observed immediately after etching GaAs and AIGaAs in C2H6:H2:Ar; much smaller changes (∼20%) were observed using CCI2F2:O2. For both gas chemistries annealing in the range 200–300°C produced the most ideal I-V characteristics in GaAs, whereas 300–400°C was required for AIGaAs.