Effect of 60Co γ-ray irradiation on electrical properties of GaAs epilayer and GaAs p–i–n diode

GaAs epilayers and p–i–n diodes structures grown using metal–organic vapor phase epitaxy were irradiated at room temperatures by 60Co γ-ray radiation with varying the dose up to 50 kGy. The carrier concentration and mobility on GaAs epilayer decreases while leakage current of p–i–n diode increases at higher radiation dose (10–50 kGy). However at lower dose (<6 kGy) carrier mobility remain same but leakage current still shows significant increase. Furthermore carrier mobility of irradiated GaAs epilayers recovers partially (68%) after annealing at 300 °C while leakage current of p–i–n diode does not show any noticeable recovery. These effects are mainly due to the creation of more deep levels compared to shallow levels as determined from photoluminescence, Hall, current–voltage and electrochemical capacitance voltage analysis.

Research highlights
► Reduction of carrier concentration and mobility of GaAs after irradiation.
► More introduction of Gallium vacancies compared to Arsenic vacancies.
► Partial conversion of shallow levels into deep levels at room temperature.
► Recovery of carrier mobility after thermal annealing at 300 °C in N2 ambient.