Most importantly, structure C always exhibits the highest electron mobility and achieves a maximum value of μ = 940 cm2/V-s. Such high electron mobility is critical
for the high-speed and high-power-switching applications. Figure 5 Dependence of 2-DEG density on gate voltage and 2-DEG mobility ( μ ) versus 2-DEG density plots. (a) Dependence of 2-DEG density on gate voltage (V g) and (b) 2-DEG mobility (μ) versus 2-DEG density for all devices. Finally, we are going to discuss the dependence of thickness and composition of QW EBL on the breakdown voltage of the HEMT. Figure 6a plots the breakdown voltage versus the GaN thickness of QW EBL, where the barrier layer of QW EBL is Al0.1Ga0.9N, and the total thickness of QW EBL is set to 10 nm. As compared to structure A (entire 10-nm-thick GaN EBL) and structure this website B (entire 10-nm-thick Al0.1Ga0.9N EBL), introducing the QW EBL considerably enhances the breakdown voltage to a much click here higher level with an average value of V br = 250 V. The ideal GaN thickness of QW EBL is around 4 to 6 nm, which provides a sufficient space Oligomycin A order to accommodate spilling electrons, prohibiting the further leakage of transport electrons into
the GaN buffer layer. Figure 6b shows the dependence of aluminum composition of QW EBL on the breakdown voltage, where the GaN thickness is set to 6 nm, and the total thickness of QW EBL is again fixed to 10 nm. Clearly, the breakdown voltage only fluctuates slightly away from the line of V br = 250 V while increasing the aluminum composition of the QW EBL from Al = 3% to Al = 20%, offering a greater tolerance for epitaxial imperfections during the fabrication of a AlGaN/GaN/AlGaN QW EBL structure. Figure 6 Breakdown voltage versus GaN thickness and dependence of aluminum composition on breakdown voltage. (a) HEMT’s breakdown voltage versus the GaN thickness of QW EBL, where the barrier layer of QW EBL is Al0.1Ga0.9N and the total thickness of QW
EBL is set to 10 nm. (b) Dependence of aluminum composition of QW EBL on the HEMT’s breakdown voltage, where the GaN thickness of QW EBL is set to 6 nm and the total thickness of QW EBL is again for fixed to 10 nm. Conclusions In conclusion, we propose a novel AlGaN/GaN/AlGaN QW EBL structure to alleviate the punchthrough effect that is generally observed on the conventional AlGaN/GaN HEMT. The introduction of AlGaN/GaN/AlGaN QW EBL leads to a better confinement of transport electrons into the 2-DEG channel, resulting in a reduction of subthreshold drain leakage current and a postponement of device breakdown. The large electric field induced at the interfaces of AlGaN/GaN/AlGaN QW EBL, which effectively depletes the spilling electrons toward the 2-DEG channel, is mainly responsible for the improved performances.