High Threshold Voltage Uniformity and Low Hysteresis Recessed-Gate Al 2 O 3 /AlN/GaN MISFET by Selective Area Growth

In this paper, a normally off Al 2 O 3 /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 het-erostructureis selectivelygrownon the template to naturally form a recessed structure. By insertion of the AlN SL, the Al 2 O 3 /AlN/GaN interface trapping and scattering effects are effectively suppressed. As a result, a low threshold voltage hysteresis ( $\Delta {V}_{\mathrm{ th}}$ , 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 ( $\mu _{\sf FE})$ of 192 cm 2 / $\text{V}\cdot \text{s}$ are obtained in Al 2 O 3 /AlN/GaN MISFET. It is a significant improvement compared with Al 2 O 3 /GaN MISFET without AlN SL. The Al 2 O 3 /AlN/GaN MISFET also exhibits a maximum drain current ( ${I}_{d,max})$ of 620 mA/mm, a low on-resistance ( ${R}_{\rm {ds}, \mathrm{\scriptscriptstyle ON}})$ of $9.6~\Omega \cdot $ mm, and a high uniformity of ${V}_{\mathrm{ th}}$ (2.5 ± 0.1 V).