InGaN/(GaN)/AlGaN/GaN normally-off metal-oxide-semiconductor high-electron mobility transistors with etched access region

Gregušová, Dagmar and Tóth, Lajos and Pohorelec, Ondrej and Hasenöhrl, Stanislav and Haščík, Štefan and Cora, Ildikó and Fogarassy, Zsolt and Pécz, Béla (2019) InGaN/(GaN)/AlGaN/GaN normally-off metal-oxide-semiconductor high-electron mobility transistors with etched access region. JAPANESE JOURNAL OF APPLIED PHYSICS, 58. pp. 1-6. ISSN 0021-4922 (print); 1347-4065 (online)

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Abstract

The proposal and processing aspects of the prove-of-concept InGaN/GaN/AlGaN/GaN metal-oxide-semiconductor (MOS) high-electron mobility transistor with etched access regions are addressed. Full strain and decent quality of the epitaxial system comprising 4 nm In0.16Ga0.84N/3 nm GaN/5 nm Al0.27Ga0.73N are observed using a high-resolution transmission-electron microscopy and by deformation profile extractions. Large negative polarization charge in the MOS gate stack provides the HEMT normally-off operation, while free electrons are populated at access regions after etching. Consecutive passivation by 10 nm Al2O3 together with annealing at 300 °C improved the Al2O3/semiconductor interface, with the threshold voltage (V T ) reaching 1 V. Improvements of the present concept in comparison to the previous one with a gate recess were proved by showing the decreased drain leakage current and increased breakdown voltage.

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