AlGaN/GaN schottky barrier diodes on silicon substrates with selective si diffusion for low onset voltage and high reverse blocking

Abstract

In this letter, a selective Si diffusion approach is proposed to improve both the forward and reverse characteristics of AlGaN/GaN Schottky barrier diodes on Si substrates. The Si diffusion layer forms a dual Schottky barrier anode structure, which results in a low Schottky barrier portion to reduce the onset voltage VON from 1.3 to 1.0 V (23%). In the same process step, the selectively diffused Si is adopted in the cathode to reduce the ohmic contact resistance RC and improve the breakdown voltage V BK. A low RC of 0.21 Ωmm and enhanced VBK up to 20% (from 1250 to 1500 V) are demonstrated, which can be attributed to the alleviated electric-field peaks around the alloy spikes beneath the ohmic contact. © 2013 IEEE.