SiO 2 film deposition and subsequent high-temperature annealing resulted in the generation of a two-dimensional electron gas (2DEG) at Al(Ga)N/GaN hetero-interfaces, of which the 2DEG was originally fully depleted. The obtained mobilities and sheet carrier concentrations were over 1100 cm 2 /Vs and 3.0 × 10 12 cm -2 , respectively. Surface energy lowering, which is proof of the generated 2DEG, was observed by electron state analysis using hard X-ray photoelectron spectroscopy. This damage-less method that selectively generates a 2DEG can contribute not only toward improving some characteristics in existing devices but also toward creating entirely novel devices.
An extrinsic electron induced by a dielectric (EID) AlGaN/GaN MOS high-electron-mobility transistor (HEMT) on Si substrate was designed and investigated. The EID structure with SiO2 deposition and subsequent high-temperature annealing, which induces two-dimensional electron gases (2DEGs) on fully depleted AlGaN/GaN hetero-epitaxial layers with thin AlGaN barrier layer, was applied to access and drift regions in the HEMT. The fabricated HEMT exhibited enhancement-mode operation with a specific on-resistance of 7.6 mΩcm2 and a breakdown voltage of over 1 kV. In addition, electron state analysis using hard X-ray photoelectron spectroscopy revealed that changes in the chemical states of Al and energy level lowering at the SiO2/AlGaN interface affect the induction of 2DEG in the EID structure. The proposed HEMTs should become a strong candidate for highly reliable high-power switching devices due to the damage-less fabrication without dry etching or fluorine plasma exposure processes on the semiconductor layers.
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