We report normally-off operation of an AlGaN/GaN recessed MOS-gate high electron mobility transistor (MOS-gate HEMT) on Si (111) substrate fabricated with the inductively coupled plasma (ICP) recessed technique. By employing a 40nm thick Al2O3 gate dielectric deposited by atomic layer deposition (ALD), the AlGaN/GaN HEMT with a gate length of 2 μm and a gate width of 10.35 mm exhibits a high threshold voltage of + 4.3 V, a specific on-resistance of 5.73 mΩ·cm2 and a saturation drain current of 0.71 A. When the gate bias (Vgs) is 0V, the breakdown voltage (BV) of the AlGaN/GaN HEMT is 400 V and the drain to source leakage current is below 320 μA with a gate-drain distance of 10μm. The on/off drain current ratio (ION/IOFF) is over 109. Under a negative gate bias (Vgs) of - 20V, the gate to source leakage current is as low as 1.8 nA. Under a positive gate bias (Vgs) of +12 V, the gate to source leakage current is only 1.6 μA. The high ION/IOFF ratio and low gate to source leakage both indicate high quality of the Al2O3/GaN interface.
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2018, Vol. 33 
