AlGaN/GaN MIS-HEMT using NbAlO dielectric layer grown by atomic layer deposition

We present an AlGaN/GaN metal-insulator-semiconductor high electron mobility transistor （MIS-HEMT） with an NbAIO high-k dielectric deposited by atomic layer deposition （ALD）. Surface morphology of samples are observed by atomic force microscopy （AFM）, indicating that the ALD NbA10 has an excellent-property surface. Moreover, the sharp transition from depletion to accumulation in capacitance voltage （C-V）curse of MIS-HEMT demonstrates the high quality bulk and interface properties of NbA10 on A1GaN. The fabricated MIS-HEMT with a gate length of 0.5 μm exhibits a maximum drain current of 960 mA/mm, and the reverse gate leakage current is almost 3 orders of magnitude lower than that of reference HEMT. Based on the improved direct-current operation, the NbA10 can be considered to be a potential gate oxide comparable to other dielectric insulators.