Xinku Liu and his team reported the vertical GaN Schottky barrier diodes (SBDs) on 2” freestanding (FS) GaN wafer from Suzhou Nanowin Science and Technology Co.,Ltd. In the SBDs they developed, using a complementary metal-oxide-semiconductor (CMOS) compatible contact materials, CMOS compatible process modules were applied, including gate stack formation and non-gold metal ohmic contact.

FS GaN substrates, grown by hydride vapor phase expitaxy (HVPE), have reached a level of the threading dislocation density less than 10⁶ cm^-2, which enables SBD devices to realize an off-state breakdown voltage V_BR of 1200 V and an on-state resistance (_Ron) of 7 mohm.cm². The fabricated FS-GaN SBDs in this work achieved a power device figure-of-merit V_BR²/_Ron of 2.1×10⁸ V²ohm-1cm^-2. In addition, the SBDs showed the highest current ratio (I_on/I_off) of ~2.3×10¹⁰ among the reported GaN SBDs in the literature.

Liu’s work has demonstrated the significance of the quality of GaN substrate to SBD fabrication with a high power operation and  a low on-state conduction loss at a given blocking voltage rating. GaN-based power rectifiers, such as SBD, show ultralow conduction loss under high voltage and high temperature operation, potentially to be used for the next generation power electronic circuit, for example, as cost-competitive power switching circuits with a supply voltage just in the range of several hundred volts.