Simulation Study on Novel GaN‐Based n−p−n Heterojunction Bipolar Transistors with a Quaternary AlGaInN Emitter and a Two‐Dimensionally Conductive Base

Herein, a simulation study on novel GaN‐based n−p−n heterojunction bipolar transistors (HBTs) with a quaternary n‐AlGaInN emitter and a thin GaInN quantum well (QW) layer inserted in its p‐GaN base is reported. The idea of the quaternary AlGaInN emitter facilitates the design and independent growth of the energy bandgaps and lattice strain. In addition, the p‐GaN base inserted with the thin GaInN QW is expected to be effective in enhancing its lateral conduction via 2D hole gases (2DHGs). The simulation results indicate that the designed GaInN QW definitely functions to generate and transport the 2DHGs and ultimately contributes to the improvement of the device performance. In other words, the lateral resistivity of the p‐GaN base is reduced from 1.8 × 10−1 to 7.0 × 10−2 Ω cm with the use of the GaInN QW insertion layer. Further, the simulation study focusing on the lateral distance between the n‐emitter and p‐base electrodes exhibits stable device characteristics for the HBT with the GaInN QW insertion layer compared with the conventional HBT structure. Dynamic analysis of the carrier concentration distribution indicates that the QW functions as a low‐resistance current path and it has the effect of avoiding the punch‐through phenomenon. Herein, GaN‐based n−p−n heterojunction bipolar transistors (HBTs) with a novel concept structure are reported. The idea of the quaternary AlGaInN emitter facilitates the design and independent growth of the energy bandgaps and lattice strain. Furthermore, the p‐GaN base inserted with the thin GaInN quantum well (QW) is expected to be effective in enhancing its lateral conduction via 2D hole gases.