Numerical Simulation and Analytical Modeling of Multichannel AlGaN/GaN Devices

In this article, we delve into the intricacies of carrier population and depletion in AlGaN/GaN multichannel structures through a combination of TCAD numerical simulations and theoretical modeling. Here, we take into account the unintentional or intentional n-type doping commonly seen in experimental multichannel devices. The impact of doping and layer thickness on the carrier population in the multichannel, as well as the carrier depletion and C – V characteristics, is investigated. The simulation results demonstrate that the doping in the AlGaN layer disrupts the balance between the 2-D electron gas (2DEG) and 2-D hole gas (2DHG), but the charge balance can be re-established with an additional pGaN layer on top of the multichannel structure. This pGaN layer can deplete the excessive electrons at high bias, resulting in a nearly flat electric field distribution. Moreover, an analytical model of the blocking electric field and conduction resistance in multichannel devices is built and validated by simulation. With this model, the impact of channel quantities on the device figure-of-merit (FOM) is studied and the optimization guideline of structure parameters is provided. This study provides key insights into the physics, performance space, and prospects of the multichannel gallium nitride (GaN) power devices.