Thermal annealing effect on the electrical properties and structural defects density of non-stoichiometric a-GaAs films

Amorphous gallium arsenide (a-GaAs) films were prepared from their constituents using the co-evaporation technique. The temperature dependence of DC conductivity for the as-deposited (fresh) As-rich and that of thermally annealed films over the temperature range 373-553 K is measured. Results of the characteristic electrical parameters indicate non-monotonic behavior during the thermal annealing range 373-423 K and a monotonic one in the range 423-553 K. Results of the density of structural defect states, using the space-charge-limited current model, are given and discussed in relation to the nature and distribution of defect states regarding their dependence on the thermal treatment.