Abstract
Lateral high-voltage single RESURF GaN MOSFETs on sapphire substrates were investigated and fabricated, with mesa isolation and Zn implantation isolation to avoid surface leakage. We demonstrated depletion-mode uGaN MOSFETs with a maximum drain current density up to 100mA/mm, a threshold voltage of -3V and a specific on-state resistance of 35mΩ-cm2 when VG=35V. The channel mobility is 26 cm2/Vs extracted from linear region at VDS=0.1V. Furthermore, we have demonstrated enhancement-mode pGaN MOSFETs with a threshold voltage of 2.37V and a maximum drain current density higher than 70mA/mm, a specific on-state resistance as low as 48mΩ-cm2 at VG=35V. The channel mobility of 21 cm2/Vs is extracted from linear region at VDS=0.1V. A pGaN MOSFET with a channel length of 3μm and a RESURF length of 25 μm shows a maximum breakdown voltage up to 120V. A lateral high-voltage InGaN MOSFET has also been investigated attempting to improve the channel mobility of GaN MOSFETs. In the fabrication of InGaN MOSFET, no ion implantation and no sintering for source and drain region was done and all fabrication has been realized at low temperatures. The depletion-mode InGaN HV-MOSFET was fabricated with the maximum breakdown voltage of 380V. The channel mobility measured from a long channel (100μm) device is 93 cm2/Vs.