Mapping of interface traps in high-performance Al2O3/AlGaN/GaN MIS-heterostructures using frequency- and temperature-dependent C-V techniques

With an in situ low-damage NH<sub>3</sub>-Ar-N<sub>2</sub> plasma pre-gate treatment, a high-quality Al<sub>2</sub>O<sub>3</sub>/GaN-cap interface has been obtained in the Al<sub>2</sub>O<sub>3</sub>/GaN/AlGaN/GaN MIS-structures. Frequency- and temperature-dependent C-V characterization techniques were developed to map the interface trap density (D<sub>it</sub>) at the dielectric/III-nitride interface, whereby a low D<sub>it</sub> of ~10<sup>12</sup>-10<sup>13</sup> cm<sup>-2</sup>eV<sup>-1</sup> in the Al<sub>2</sub>O<sub>3</sub>/GaN/AlGaN/GaN MIS-structures was extracted. The mechanism for the high-quality interface was validated to be effective removal of native oxide and the subsequent formation of a monocrystal-like nitridation inter-layer on the GaN surface. Both D<sub>it</sub> mapping and the pre-gate treatment techniques are of significance for the improvement of III-nitride MIS-HEMTs.

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