Origin of reverse leakage current in n-type nanocrystalline diamond/p-type silicon heterojunction diodes

Abstract

The reverse leakage current in n-type nanodiamond film/p-type silicon wafer heterojunction diodes is examined as a function of the film conductivity. We observe that as the delocalization of carriers in the films becomes stronger, the leakage current becomes larger (from 10−3 to 101 A cm−2). The major leakage source is attributed to the minority carriers from the π defect bands introduced by sp2 carbon. Both a current injection barrier and a dielectric barrier at the interface are found to be small (∼0.6 eV). The simultaneous reduction in leakage current and turn-on voltage for low-loss diodes needs optimization of the interfacial valence band connection.