High Power AlGaN/GaN Schottky Barrier Diode with 1000 V Operation

Abstract

We investigated an AlGaN/GaN Schottky barrier diode (SBD) with a field plate structure for a high breakdown voltage. The AlGaN/GaN heterostructure was grown by MOCVD. The AlGaN buffer was grown on the Si (111) substrate and Al0.25Ga0.75N (25 nm)/ GaN (1000 nm) was grown on the buffer layer. The AlGaN/GaN heterostructure without any crack was obtained. After that, a Schottky barrier diode was fabricated using an AlGaN/GaN heterostructure. In order to obtain a high breakdown voltage, a gate field plate structure was used. SiO₂ was formed on the AlGaN layer using a plasma chemical vapor deposition. The Schottky electrode of Ni/Au was partially deposited on the SiO₂ film towards the ohmic region. The length of field plate structure was also changed to investigate the effect. Ti/Al-silicide was used for an ohmic electrode of SBD. The contact resistance of ohmic electrodes was 8E-6 ohmcm².

The current-voltage characteristics of an AlGaN/GaN SBD were measured. The reverse breakdown voltage of the diode was also over 1000 V and the reverse leakage current was below 1.5E–6 A/mm.