A 3-kV GaN MISHEMT With High Reliability and a Power Figure-of-Merit of 685 MW/cm²

In this letter, GaN metal–insulator–semiconductor high electron mobility transistors (MISHEMTs) are fabricated on Si substrates with an ultra-high breakdown voltage of over 3 kV using a 90-nm in situ $\textrm {SiN}_{\mathrm { X}}$ layer as both the gate dielectric and surface passivation. The devices exhibit low off-state leakage current (on/off ratio of $10{^{{9}}}$ ), high forward gate breakdown voltage (>122 V), and state-of-the-art figure of merit (685 MW/cm2). Moreover, the reliability of the in situ $\textrm {SiN}_{\mathrm { X}}$ dielectric is evaluated through the high-temperature gate bias test. The results are fitted with a Weibull distribution, estimating a 10-year estimation of 100 ppm. The maximum gate-source voltage of over 70 V is obtained. This letter presents a strategy for mass producing GaN-on-Si MISHEMTs with high breakdown voltage and reliability.