Increased Breakdown Voltage in Vertical Heterostructure III-V Nanowire MOSFETs with a Field Plate

Vertical III-V heterostructure MOSFETs exhibit outstanding performance at reduced supply voltages. In this letter, we report on a novel process of extending high-speed device operation towards higher voltages. The device vertical geometry allows for engineering a field plate by covering the nanowire drain area with a 10-nm-thick SiO2 film. The film acts as a field moderator in the device drain region. Reference devices without a field plate exhibit a transconductance of 2.5 mS/ $\mu \text{m}$ , while devices with a 120-nm-long field plate show 1.5 mS/ $\mu \text{m}$ but a three times increase in breakdown voltage. Measurements show that the field-screening effect attributes to reduced band-to-band tunneling and impact ionization, thereby reducing the parasitic bipolar effect in the MOSFET channel as well. The devices show promise in applications in circuits and systems requiring large power-handling.