Reverse-biased induced mechanical stress in AlGaN/GaN power diodes

The piezoelectric stress distribution induced in the GaN layer of AlGaN/GaN Schottky Barrier Diodes (SBDs) under a DC reverse voltage of -250 V is directly measured using micro-Raman spectroscopy. The highest piezoelectric stress measurable near the anode fieldplate edge is 380 ± 40 MPa, which is similar to the stress measured in an AlGaN/GaN SBD under reverse-bias cycling at -400 V in a high voltage DC-DC boost converter circuit. Continuous operation of the SBD under this stress cycling condition may lead to cracking of the GaN layer and in turn degradation of the device, which may pose a reliability concern in such boost converter circuits.