GaN Smart Discrete power devices

Abstract

GaN “Smart Discrete” power devices were realized using the AlGaN/GaN-on-Si platform, where two built-in intelligent self-protection functions were demonstrated. First, an AlGaN/GaN normally-off high electron mobility transistor (HEMT) with reverse drain blocking capability was realized, featuring a Schottky contact controlled drain barrier. Compared to the Schottky drain structures, the new design exhibits only a 0.55 V onset voltage in the forward biased “ON” state, while effectively blocks the reverse current conduction. The device fabrication is also free of extra photomask and process steps. Second, an AlGaN/GaN lateral field-effect rectifier (L-FER) with intrinsic “ON” state current limiting capability was fabricated, featuring a Schottky controlled depletion- mode (D-mode) channel extension (length of L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D</sub> ) beyond the ohmic contact at the cathode electrode, where the on-state current of the new rectifiers are self-limited at 4.59 kA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> (L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D</sub> = 1.3 μm) and 3.56 kA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> (L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D</sub> = 1.9 μm) at room temperature. The current limiting level shows a negative temperature coefficient (TC) that is desirable for thermal stability.