Ar plasma etching of n-type (Si doped) GaAs introduces several electron traps (Ec - 0.04 eV,
Ec - 0.07 eV, Ec - 0.19 eV, Ec - 0.31 eV, Ec - 0.53 eV, and Ec - 0.61 eV). The trap, Ec - 0.04 eV,
labelled E10 and having a trap signature similar to irradiation induced defect E1, appears to be
metastable. Ec - 0.31 eV and Ec - 0.61 eV are metastable too and they are similar to the M3/M4
defect configuration present in hydrogen plasma exposed n-GaAs.