High Figure-of-Merit (${V}_{\text{BR}}^{\text{2}}$ /${R}_{\text{ON}}$ ) AlGaN/GaN Power HEMT With Periodically C-Doped GaN Buffer and AlGaN Back Barrier

Abstract

In this paper, we investigated characteristics of AlGaN/GaN high-electron mobility transistors (HEMTs) with high resistive buffer structure consisted of periodically carbon-doped (PCD) GaN buffer layer and AlGaN back barrier layer. The PCD structure was proposed for reducing undesirable trapping effects, which resulted in effective suppression of the current collapse compared to that in conventional carbon buffer structure. To further improve the dynamic performances of the device and to increase the electron confinement of the 2-D electron gas (2-DEG) channel, AlGaN back barrier was inserted between the GaN channel and the PCD buffer layer, which results in greatly improved current collapse with slightly improved 2-DEG mobility compared to those of the device without back barrier. The OFF-state leakage current of the device with back-barrier is about 2 orders lower in magnitude than that of device without back barrier, which leads to the breakdown voltage of 2 kV and figure of merit of 2.27 GV $^{2} \Omega ^{-1}$ cm−2 for the device with LGD of $10~{{\mu }}\text{m}$ , one of the highest values ever reported for the GaN-based HEMTs.