Design Space of III-N Hot Electron Transistors Using AlGaN and InGaN Polarization-Dipole Barriers

Abstract

Transistor operation by common emitter (CE) current modulation is shown for the first time in III-N hot electron transistors (HETs). The emitter and collector barriers (φ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BE</sub> and φ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BC</sub> ) are implemented using Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.45</sub> Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.55</sub> N and In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.1</sub> Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.9</sub> N layers as polarization dipoles, respectively. CE modulation is achieved by increasing the E-B barrier height beyond the B-C barrier height by increasing the Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.45</sub> Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.55</sub> N thickness (t). Similar CE performance is seen in the identical HET structures grown on both bulk GaN and sapphire. A maximum α of ~0.3 is achieved using a GaN base thickness of 10 nm. The InGaN dipole used as the collector barrier is shown to be instrumental in enabling ohmic base contacts, low base sheet resistance, and low collector leakage, simultaneously.