Hongyu Guo

Excellent-Performance AlGaN/GaN Fin-MOSHEMTs with Self-Aligned Al

AlGaN/GaN fin-shaped metal-oxide-semiconductor high-electron-mobility transistors (fin-MOSHEMTs) with different fin widths (300nm and 100 nm) on sapphire substrates are fabricated and characterized. High-quality self-aligned Al2O3 gate dielectric underneath an 80-nm T-shaped gate is employed by aluminum self-oxidation, which induces 4 orders of magnitude reduction in the gate leakage current. Compared with conventional planar MOSHEMTs, short channel effects of the fabricated fin-MOSHEMTs are significantly suppressed due to the trigate structure, and excellent dc characteristics are obtained, such as extremely flat output curves, smaller drain induced barrier lower, smaller subthreshold swing, more positive threshold voltage, higher transconductance and higher breakdown voltage.

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In this paper, we report on a novel E-mode AlGaN/GaN gates-seperating groove heterostructure field-effect transistor (GSG HFET). The current turn-on/off is controlled by changing gate voltage to regulate the horizontal energy band between the double gates. A threshold voltage of 0.23 V and a high drain current density of 851 mA/mm are obtained in GSG HFET. Compared with the proposed depletion-mode device, the maximum drain current of the GSG HFET deceases slightly (about 7%). It is noteworthy that the threshold voltage is less sensitive to the etching time. The devices show high-uniformity threshold voltage of 0.23 V within wide etching time range from 5 to 9 min.