GaAs radiation damage induced by electron cyclotron resonance plasma etching with SF6/CHF3

After SF6/CHF3 plasma exposure, the sheet resistance of Si-doped GaAs layers is higher because of carrier reduction near the surface and sputter etched surface, and this electrical and physical damage is found to depend on rf-power and µ-wave power. The carrier reduction can be almost restored by annealing at 450° C for 30 min. Exposures to He plasma or CHF3 plasma cause more extreme carrier reduction than does exposure to SF6 plasma, indicating that the carrier reduction in the damaged layers is predominantly due to the bombardment by low-mass fragments such as H and He. Low-temperature (4.2 K) photoluminescence of SF6/CHF3-plasma-exposed GaAs shows a broad and complicated spectrum (ranging from 1.25 to 1.43 eV) related to defect-complex by incorporation of hydrogen.