Temperature Dependence of Leakage Current in InAs Avalanche Photodiodes

Measurement and analysis of the temperature dependence of bulk and surface leakage currents in InAs avalanche photodiodes have been performed between 77 K and 290 K. At unity gain, SU-8 passivated InAs photodiodes have low dark current densities of 100 mA/cm² at 290 K and 150 nA/cm² at 77 K. An avalanche multiplication factor of 25 was measured at 13 V and 19.5 V at 290 K and 77 K, respectively. The photodiodes exhibit dynamic resistance-area products, calculated at 0.1 V of 34 Ω-cm² at 290 K and 910 MΩ-cm² at 77 K. Our analysis showed that between the temperatures of 200 K and 290 K, the bulk leakage current is proportional to n_i² whereas the surface leakage current is proportional to n_i from 77 K to 290 K, where n_i is the intrinsic carrier concentration. The activation energies deduced were 0.36 eV and 0.18 eV suggesting diffusion dominated bulk current and generation and recombination dominated surface current.