Mechanism of reverse current in the Al/p-InP schottky diodes

Reverse current-voltage characteristics of the Al/p-InP Schottky diodes based on Zn-doped InP epilayers were measured in relation to bias and temperature. Temperature dependence of reverse current is characterized by the activation energies of 0.75 and 0.51 eV in the high-temperature region and at temperatures T<280 K, respectively. Results are explained by the phonon-assisted tunneling generation of charge carriers from the surface states of a semiconductor with regard to the Frenkel emission mechanism. It is found that, in the low-temperature region, tunneling occurs via the centers with energy levels of 0.51 eV. Comparing experimental results with theory, we estimated electric-field strength in the barrier at (5–13)×10⁷ V/m and the surface density of the hole charge in the boundary layer of the semiconductor.