AlGaN/GaN Schottky Barrier Diodes on Silicon Substrates With Selective Si Diffusion for Low Onset Voltage and High Reverse Blocking

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 V-ON 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 R-C and improve the breakdown voltage V-BK. A low R-C of 0.21 Omega.mm and enhanced V-BK 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.