1200V E-mode GaN Monolithic Integration Platform on Sapphire with Ultra-thin Buffer Technology

This paper firstly reported the 1200V enhancement-mode (E-mode) Gallium Nitride (GaN) based monolithic halfbridge (HB) integration platform on Sapphire substrate with ultra-thin buffer layer. Thanks to the specially designed ultra-thin un-doped buffer on Sapphire substrate, the shallow trench between high-side devices and low-side devices achieves over 3000V isolation without crosstalk and substrate biasing effects. Meanwhile, the breakdown voltage (BV) of high voltage (HV) p-GaN gate high electron mobility transistor (p-GaN HEMT) reaches 2300V, the normalized BV is 140% of GaN-on-SOI device. Low off-state drain leakage current is also achieved (~0.1μA/mm@1200V@175℃) due to the isolated substrate and thin buffer. Other electrical characteristics up to 175℃ of HV and low voltage devices are also evaluated. The excellent high temperature performances demonstrate the tolerance of the integration platform to low thermal conductance of Sapphire. Finally, the HV monolithic HB circuits are demonstrated to work under 800V-switching conditions at 175℃ by a boost converter.