Abstract
In this study, a 50-nm Al0.05Ga0.95N back barrier (BB) layer was used in an AlGaN/GaN high-electron-mobility transistor between the two-dimensional electron gas channel and Fe-doped/C-doped buffer layers. This BB layer can reduce the channel layer. The BB layer is affected by doped carriers in the buffer layer and the conduction energy band between the channel and the buffer layers. The Ion/Ioff ratio of the BB device was 4.66 × 105, and the ratio for the device without BB was 1.91 × 103. Lower leakage currents were obtained in the BB device because of the higher conduction energy band. The 0.25-μm gate length device with the BB exhibited a high current gain cutoff frequency of 24.4 GHz, and power gain cutoff frequency of 73 GHz.
Highlights
AlGaN/GaN high-electron-mobility transistors (HEMTs) have potential applications in next-generation high-power and microwave devices
In this study, a back barrier (BB) layer was used to reduce the leakage from electron tunneling into the buffer layer and, effectively, confine electrons to the 2DEG
The AlGaN/GaN HEMT was grown on 6-inch Si substrates through metal organic chemical vapor deposition (MOCVD) with/without the Fedoped/C-doped GaN buffer layer
Summary
AlGaN/GaN high-electron-mobility transistors (HEMTs) have potential applications in next-generation high-power and microwave devices. GaN exhibits high electron mobility, breakdown voltage, electron saturation speed, and thermal conductivity, because of the wide band gap. Several studies have presented doped iron (Fe) [3,4,5] or carbon (C) [2,6,7,8] in the buffer layer to suppress buffer defects. The doped buffer devices with impurities can result in current collapse (CC), resulting in the buffer traps inducing threshold voltage (VTH) shifts [9]. When a high drain voltage was applied, some electrons from the two-dimensional electron gas (2DEG) were captured by dislocations or traps in the buffer layer, which caused reliability problems. In this study, a back barrier (BB) layer was used to reduce the leakage from electron tunneling into the buffer layer and, effectively, confine electrons to the 2DEG
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