Bias-Insensitive High Linearity of N-Polar Deep Recess GaN HEMTs With Regrown GaN Cap

Nitrogen polar (N-polar) deep-recess high electron mobility transistors (HEMTs) with a charge sheet in the cap layer have been investigated for increased current and bias-insensitive linearity. The charge sheet was introduced by a regrown GaN cap layer on top of the in-situ GaN cap layer. A Schottky gate process integrated with a SiN recess-trench sidewall coverage was developed to reduce gate leakage through the cap. The devices showed a high knee current of 2 A/mm with a 0.36 Ω·mm on-resistance. Additionally, a broad gm1 profile of > 400 mS/mm is exhibited and maintained in pulsed-IV measurements, withgm3values below 27 mS/(mm∙V2) withinVGS= –5 V to 0 V atVDS= 2 V. Furthermore, a higher OIP3/PDCfigure of merit of ~15 dB was observed in two-tone measurements centered at 10 GHz than previously reported, maintaining ≥ 10 dB atIDS,Q= 90 to 605 mA/mm, indicating ultra-high bias-insensitive device linearity. Pad de-embeddedfT/fmax= 103.9 GHz / 159.8 GHz was achieved. These superior properties demonstrate good potential for high-performance bias-insensitive linear RF receiver applications.