High-Precision Small-Signal Model for Double-Channel–High-Electron-Mobility Transistors Based on the Double-Channel Coupling Effect

This paper presents a new small-signal model for double-channel (DC)-high-electron-mobility transistors, developed through an analysis of the unique coupling effects between channels in devices. Unlike conventional single-channel HEMTs, where electrons only transport laterally in the channel, DC-HEMTs exhibit additional vertical transport between the two channels along the material direction. This double-channel coupling effect significantly limits the applicability of traditional small-signal models to DC-HEMTs. Firstly, the coupling effect between the two channels is characterized by introducing the double-channel coupling sub-model, which consists of <i>R</i>_GaN, <i>R</i>_AlN, and <i>C</i>_AlN. At the same time, by introducing parameters gm_{_upper} and gm_{_lower}, the new model can accurately characterize the properties of double channels. Secondly, initial values for <i>R</i>_GaN, <i>R</i>_AlN, and <i>C</i>_AlN are calculated based on the device's physical structure and material properties. Similarly, initial values for <i>gm</i>_{_upper} and <i>gm</i>_{_lower} are derived from the device's DC measurement and TCAD simulation results. Furthermore, a comprehensive parameter extraction method enables the optimized extraction of intrinsic parameters, completing the model's construction. Finally, validation of the model's fitting reveals a significantly reduced error compared to traditional small-signal models. This enhanced accuracy not only verifies the precise representation of the device's physical characteristics but also demonstrates the model's effectiveness.