Suppression of killer defects in diamond vertical-type Schottky barrier diodes

Abstract

Vertical architectures in diamond Schottky barrier diodes (VSBDs) are favorable for realizing high-current operation. However, a major obstacle affecting performance is the presence of killer defects which are thought to originate from heavily B-doped p+ substrates. Here, we introduced a buffer layer to suppress the extended defects from p+ substrate to epitaxial layer, called metal-assisted termination. Significant reduction of band-A luminescence in cathodoluminescence spectra was confirmed, indicating a large improvement in crystallinity. VSBDs showed highly uniform rectifying actions with suppressed leakage currents. The electric field strength was increased from 1.9 to 5.0 MV cm-1 when a buffer layer was inserted.