High-Performance Enhancement-Mode Al2O3/AlGaN/GaN-on-Si MISFETs With 626 MW/cm2 Figure of Merit

In this paper, the partial gate recess for performance improvement of enhancement-mode (E-mode) GaN power devices is experimentally demonstrated. The gate recess with a careful control of the recess depth was performed with an optimized recessed barrier thickness of similar to 1.5 nm that is thin enough to completely deplete the 2-D electron gas channel in the gate region. Meanwhile, the remaining barrier preserves the as-grown quantum well of the heterostructure physically intact and thus, effectively mitigates the lattice damage caused by gate recess. The fabricated E-mode Al2O3/AlGaN/GaN MISFETs deliver a threshold voltage (V-TH) of +1.5 V. The maximum drain current density (I-D,I-max) and transconductance (G(m,max)) are 693 mA/mm and 166 mS/mm, respectively. The MISFETs with an L-GD of 10 mu m feature an OFF-state breakdown voltage of 860 V at a leakage current of 1 mu A/mm. The corresponding specific ON-resistance (R-ON,R-sp) is as low as 1.18 m Omega.cm(2) yielding a high-power figure of merit of 626 MW/cm(2). In comparison with the reference MOSFETs by fully gate recess, the respectably improved device performance of the MISFETs attributes to the enhanced electron mobility achieved by the partial gate recess.