Electrical damage in n-GaAs due to methane-hydrogen RIE

In order to investigate the electrical damage induced in Si-doped GaAs by CH 4 /H 2 RIE, electrical characterisations (I-V, C-V) of Schottky diodes fabricated on the dry-etched surface were performed. After RIE carried out at 1.3 W cm -2 , the Schottky barrier height decreases from 0.79 V to 0.53 V. Successive wet chemical etchings of the dry-etched surface show that the in-depth extent of this damage is at least 50 nm. Doping profiles, derived from conventional C-V analysis show a decrease in free-carrier concentration in the surface after RIE. The extent of this passivation is inversely dependent on the initial doping level. This effect is attributed to a chemical neutralisation of the doping centres by atomic hydrogen. The reactivation energy for recovery of the donor activity is around 1.75 eV.