High Threshold Voltage Uniformity and Low Hysteresis Recessed-Gate Al2O3/AlN/GaN MISFET by Selective Area Growth

In this paper, a normally off Al2O3/AlN/GaN MISFET on Si substrate for achieving high threshold voltage stability and uniformity is obtained based on selective area growth. A thin AlN space layer (SL, ~1 nm) is adopted to GaN-based template, and the AlGaN/GaN heterostructure is selectively grown on the template to naturally form a recessed structure. By insertion of the AlN SL, the Al2O3/AlN/GaN interface trapping and scattering effects are effectively suppressed. As a result, a low threshold voltage hysteresis (Δ Vth, 80 mV at maximum gate sweep voltage of 10 V by dc I-V measurement and smaller than 200 mV in linear region by pulse I-V measurement) and a high peak field-effect mobility (μFE) of 192 cm2/V·s are obtained in Al2O3/AlN/GaN MISFET. It is a significant improvement compared with Al2O3/GaN MISFET without AlN SL. The Al2O3/AlN/GaN MISFET also exhibits a maximum drain current (Id,max) of 620 mA/mm, a low on-resistance (Rds,ON) of 9.6 Ω·mm, and a high uniformity of Vth(2.5 ± 0.1 V).