We have investigated the etch rates, residual lattice damage, surface morphologies and chemistries of InP, InGaAs, AlInAs and GaAs plasma etched in electron cyclotron resonance (ECR) CH4/H2/Ar discharges. The etch rates of InP and InGaAs increase linearly with additional RF biasing of the substrate, and are approximately a factor of two faster than for GaAs. Under our conditions the etch rate of Al0.52Ga0.48As is very low (˜25 Å - min−1) even for the addition of 100 V RF bias. In all of these materials the residual damage layer remaining after dry etching is very shallow (˜20 Å) as evidenced from Schottky barrier height and photoluminescence measurements combined with wet chemical etching. InP shows significant P depletion with the addition of RF biasing during the ECR etching while GaAs retains a near-stoichiometric surface. Hydrogen passivation of shallow donors in n-type GaAs occurs to a depth of ˜3000,Å during exposure to the CH4/H2/Ar discharge for long periods (60 mins). The surface morphologies of the In-based materials become roughened for etching with the addition of RF biasing while GaAs displays smooth, residue-free surfaces under these conditions.