ELECTRICAL CHARACTERIZATION OF VERY-LOW ENERGY (0-30 EV) CL-RADICAL ION-BEAM-ETCHING INDUCED DAMAGE USING 2-DIMENSIONAL ELECTRON-GAS HETEROSTRUCTURES

Damage induced by very low energy (30 eV) Cl reactive ion beam etching (RIBE) and radical etching (RE) has been electrically characterized. GaAs/n-AlGaAs two-dimensional electron gas heterostructures were used as damage sensitive probes. Sheet carrier concentrations and Hall mobilities were measured at 77 K, under dark as well as illuminated conditions. By carefully designing the sample structure, the damaged layer thickness could be estimated by comparing dark and illuminated data. In case of RE, no degradation was detected at depths as shallow as 25 nm from the etched surface. For 30 eV-RIBE, the damage was detected but found to be reasonably small (38% decrease in electron mobility) and shallow (< 50 nm). Electrical and optical damage are compared briefly.