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

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 ( $\phi _{\mathrm {\mathbf {BE}}}$ and $\phi _{\mathrm {\mathbf {BC}}}$ ) are implemented using Al 0.45 Ga 0.55 N and In 0.1 Ga 0.9 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 0.45 Ga 0.55 N thickness ( $t$ ). Similar CE performance is seen in the identical HET structures grown on both bulk GaN and sapphire. A maximum $\alpha $ of $\sim 0.3$ 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.