GaN‐Based Monolithic Inverter Consisting of Enhancement‐ and Depletion‐Mode MOSFETs by Si Ion Implantation

Abstract

Herein, the effects of Si ion implantation on GaN in a dose range of 1011–1014 cm−2 towards a GaN‐based monolithic inverter circuit consisting of n‐channel enhancement‐ and depletion‐mode MOSFETs (E‐MOSFET and D‐MOSFET) are investigated. The implantation dose dependence is investigated by capacitance–voltage (C–V) measurement of Si‐implanted GaN metal–oxide–semiconductor (MOS) capacitors. Enhanced stretches of C–V curve in voltage bias direction in higher dose samples and its nonlinear dependence on Si dose are discussed. Characteristics of E‐ and D‐MOSFET fabricated on p‐GaN with Mg doping concentration of on sapphire substrate are presented. The operation of E‐ and D‐MOSFET with normally‐on and normally‐off characteristics is obtained. To further improve MOSFET characteristics, a low Mg concentration p‐GaN layer with [Mg] of 1×1017 cm−3 on GaN substrate is used for monolithic E‐ and D‐MOSFET fabrication. Improved E‐MOSFET characteristics are confirmed by effective mobility of 38 cm2 (V s)−1. The successful operation of an enhancement/depletion (E/D)‐type inverter with a maximum voltage gain 1.5 beyond unity is presented in monolithic E‐ and D‐MOSFET on the same chip.