Atomic Layer Deposition of $\hbox{SiO}_{2}$ for AlGaN/GaN MOS-HFETs

This letter investigates the electrical properties of SiO<sub>2</sub> gate dielectric on GaN heterostructures deposited by atomic layer deposition (ALD). ALD SiO<sub>2</sub> has a dielectric constant of 3.9 and a bandgap of 8.8 eV. ALD SiO<sub>2</sub> provides a good interface to GaN and minimizes the interfacial layer growth. The threshold voltage of metal-oxide-semiconductor heterojunction field-effect transistors with ALD SiO<sub>2</sub> dielectric is -1.5 V, owing to a fixed charge concentration of -1.6 × 10<sup>12</sup> cm<sup>-2</sup>. It was also found that devices with ALD SiO<sub>2</sub> dielectric exhibit three orders of magnitude reduction in gate leakage current compared to conventional Schottky gate HFETs.

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