We report the first demonstration of fully-vertical power MOSFETs on 6.6-μm-thick GaN grown on a 6-inch Si substrate by metal-organic chemical vapor deposition (MOCVD). A robust fabrication method was developed based on a selective and local removal of the Si substrate as well as the resistive GaN buffer layers, followed by a conformal deposition of a 35-μm-thick copper layer on the backside by electroplating, which provides excellent mechanical stability and electrical contact to the drain terminal. The fabrication process of the gate trench was optimized, improving considerably the effective mobility at the p-GaN channel and the output current of the devices. High performance fully-vertical GaN-on-Si MOSFETs are presented, with low specific on-resistance (Ron,sp) of 5 mΩcm2 and high off-state breakdown voltage (BV) of 520 V. Our results reveal a major step towards the realization of high performance GaN vertical power devices on cost-effective Si substrates.

We demonstrate the first GaN vertical transistor on silicon, based on a 6.7-μm-thick n-p-n heterostructure grown on 6-inch silicon substrate by metal organic chemical vapor deposition (MOCVD). The devices consist of trench-gate quasi-vertical metal–oxide–semiconductor field-effect transistors (MOSFETs) with a 4 μm-thick drift layer, exhibiting enhancement-mode (E-mode) operation with a threshold voltage of 6.3 V and an on/off ratio of over 108. A high off-state breakdown voltage of 645 V along with a specific on-resistance of 6.8 mΩ·cm2 were achieved thanks to the high-quality 4 μm-thick GaN drift layer presenting a relatively low defect density and very high electron mobility (720 cm2/V·s). This excellent performance represents a major step towards the realization of high-performance GaN vertical power transistors on low-cost silicon substrates.

In this paper, we present a systematic investigation of metal-organic chemical vapor depositiongrown in situ SiN as the gate dielectric and surface passivation for AlGaN/GaN metal insulator semiconductor high electron mobility transistors (MISHEMTs). The dielectric constant and breakdown field of the in situ SiN were extracted from devices with varied gate dielectric thicknesses. Using frequency-dependent capacitance-voltage and parallel conductance methods, we obtained a low trap density of ~3 x 10 ¹² cm ^-2 eV ^-1 at the SiN/AlGaN interface. The MISHEMTs with a source-drain distance of 3 μm show a maximum drain current of 1560 mA/mm and a high on/off current ratio of 10 ⁹ . The device threshold voltage (V _th ) stability was assessed by means of both negative and positive gate stress measurements, as well as temperature-dependent I _D -V _G measurements. We observed a minimal V _th shift of ~0.4 V under both 3000 s gate stress of V _GS = 4 V and up to 200 °C thermal stimulation. Furthermore, combining the in situ SiN with plasma-enhanced chemical vapor deposition SiN, we developed a bilayer passivation scheme for effective suppression of current collapse. Employing the high-quality in situ SiN, we have demonstrated large-area GaN MISHEMTs on Si with a gate width of 20 mm, showing a low off-state leakage of 2 μA/mm at 600 V and a low dynamic/static ON-resistance ratio. The device results show great advantages of employing in situ SiN in D-mode GaN MISHEMTs for high-efficiency power switching applications.

We demonstrate for the first time the monolithic integration of vertical GaN MOSFETs with freewheeling Schottky barrier diodes (SBD), based on a 6.7-μm-thick n-p-n heterostructure grown on 6-inch silicon substrates by metal organic chemical vapor deposition. The anode of the SBD is integrated in the source pad of the MOSFET and the cathode is directly connected to the MOSFET drain through the bottom n+−GaN layer, eliminating the need of any metal wire interconnection. This monolithic integration scheme offers reduced footprint, minimized parasitic components and simplified packaging. The integrated MOSFET-SBD showed enhancement-mode operation with a threshold voltage of 3.9 V, an on/off ratio of over 108 and a dramatic improvement in reverse conduction, without degradation in on-state performance from the integration of the SBD. The integrated GaN-on-Si vertical SBD exhibited excellent performance, with a specific on-resistance of 1.6 mΩ·cm2, a turn-on voltage of 0.76 V, an ideality factor of 1.5, along with a breakdown voltage of 254 V. These results reveal the promising potential of emerging GaN vertical devices for future power converters.

In this letter, we demonstrate GaN-on-Si p-i-n diodes with high breakdown voltage and state-of-the-art Baliga's figure of merit (BFOM) among GaN-on-Si vertical devices. The growth and doping of the GaN drift layer were optimized, leading to a remarkable electron mobility of 720 cm2/Vs for a Si doping level of 2 × 1016 cm ^-3 . With a 4 μm-thick drift layer, we achieved an excellent breakdown voltage of 820 V and ultra-low specific on resistance (Ron,sp) of 0.33 mΩcm ² . This results in a BFOM of 2.0 GW/cm ² , the highest value reported for GaN-on-Si vertical diodes. These results reveal the excellent prospect of GaN-on-Si for cost-effective vertical power devices.

This paper reports a novel voltage-controlled light emitter with fast switching speed and dimming capability using a monolithically integrated GaN HEMT-LED device. The integrated HEMT-LED device, with a transconductance of 113 mS/mm and large light emitting area (450 ×470 μm2), exhibits a fast switching speed of 15 MHz. When functioning as an optical transmitter, a data rate of 16.7 Mbit/s was demonstrated. By reducing the duty cycle of the pulsed gate voltage from 100% to 0.1%, the light intensity decreased accordingly, and a linear pulse-width modulation (PWM) dimming performance with a wide dimming range (0.1% to 100%) and high dimming ratio (51,282:1) was achieved.