Schottky-Ohmic Drain AlGaN/GaN Normally Off HEMT With Reverse Drain Blocking Capability

Abstract

In this letter, we propose an AlGaN/GaN normally off high-electron mobility transistor (HEMT) with reverse drain blocking capability. The device features a Schottky-ohmic drain electrode in which a Schottky-controlled normally off channel is inserted between the gate and the conventional ohmic drain contact. Under negative reverse drain bias, the normally off channel provides an energy barrier that effectively blocks the reverse current conduction while contributing only 0.55 V onset voltage in the forward-biased on state. In a device with a gate-drain distance of 9 m, a reverse blocking voltage of -321 V was obtained at V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">GS</sub> = 0 V, comparable with the forward blocking voltage of 351 V; at V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">GS</sub> = 3 V, the reverse blocking voltage was -276 V. The new HEMT also exhibits no degradation in drain saturation current and does not need extra photomask or process steps to fabricate. When forward biased at V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">GS</sub> = 3 V , the proposed device achieved a specific on resistance of 1.97 mΩ · m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .