Admittance spectroscopy of electron irradiated p-type indium phosphide

Admittance spectroscopy measurements have been carried out on electron irradiated ITO/p-InP and Au/p-InP diodes, and their results have been compared with those obtained from I-V-T properties, deep level transient spectroscopy and thermally stimulated capacitance measurements. It was found that a high fluence of electron radiation, 10 ¹⁶ cm^-2 induces a dominant defect HD1 with a density of ~1.3×10¹⁶ cm^-3, much higher than that of defects H3 and H4. A further defect HD2 was also observed with a density of ~3×10¹⁵ cm^-2, which only appeared after annealing at T_A>90°C. It is defect HD1 which is held responsible for the removal of most carriers, the increase of series resistance and the subsequent degradation of solar cells, and not defects H3 and H4 as is normally accepted. Defect HD1 has a low threshold annealing temperature of ~70°C, and is completely removed at 100°C, more than 30°C lower than that of defects H3 and H4