Effect of ECR plasma on the luminescence efficiency of InGaAs and InP

InGaAs and InP exposed to N2 or Ar ECR plasmas show reduced photoluminescence intensity. The extent of the degradation depends on both the microwave power level and any additional r.f. power applied to increase the energy of ions in the discharge. Annealing at 200°C restores approx. one-third of the initial luminescence efficiency in both materials, but HF removal of the native oxide increases the PL intensity to ∼80% in InGaAs and ∼40% in InP. The mechanism for the degraded optical output from these materials is creation of both interface and bulk states. The latter are present to depths of ≥200 Å and are more prevalent in InP. Passivation of the surfaces using (NH4)2S treatment completely restores the PL intensity in InGaAs, but not in InP. ECR deposition of SiNx shows excellent conformity around the gate contact of submicron high electron mobility transistors, and an absence of the rabbit-ears typically present with conventional PECVD.