Effect of buffer iron doping on delta-doped beta-Ga2O3 metal semiconductor field effect transistors

We report on the effect of iron (Fe)-doped semi-insulating buffers on the electron transport and DC-RF dispersion in Si delta (delta)-doped beta-Ga2O3 metal-semiconductor field effect transistors. The effect of the distance between the 2-dimensional electron gas and the Fe-doped region was investigated, and Fe doping in the buffer was found to have a significant effect on the transport properties. It was found that buffers thicker than 600 nm can enable better transport and dispersion properties for field effect transistors, while maintaining relatively low parasitic buffer leakage. This work can provide guidance for the use of Fe-doped insulating buffers for future Ga2O3 based electronics. Published by AIP Publishing

Ion irradiation-induced interface mixing and the charge trap profiles investigated by in situ electrical measurements in Pt/Al₂O₃/β-Ga₂O₃MOSCAPs

In situ I - V and C-V measurements were performed during the 120 MeV Au9+ ion irradiation on the Pt/Al2O3/β-Ga2O3, metal-oxide-semiconductor capacitors (MOSCAPs), to comprehend the swift heavy ion (SHI)-induced effects at the interface and in the device performance. At a maximum fluence of 2× 1012 ions/cm2, the I-V data showed a rise in the reverse leakage current by four orders of magnitude compared to the pristine device. The trap level (below the conduction band of Al2O3) from Poole-Frenkel emission exhibits a variation from ∼ 1.1 to 0.91 eV. The conduction band offset (φB) of Al2O3/β-Ga2O3 changes from 1.48 to 1.25 eV as estimated under the Fowler-Nordheim tunneling mechanism. In situ C-V measurements show a significant shift in the flat band voltages and increased oxide in the border and interface due to charge trapping. The X-ray photoelectron spectroscopy (XPS) measurements of Al 2p and O 1s core levels revealed the pre-existing oxygen defects in Al2O3, which increase with fluence. The deconvoluted peaks of Al 2p at 74.6 eV designated to Al-sub oxide and the O 1s peak variation in the FWHM signifies the increase in the O defects. Cross-sectional transmission electron microscopy (XTEM) measurements on the irradiated device (at 2× 1012 ions/cm2) revealed a modulated interface of Al2O3/β-Ga2O3 and the formation of an interlayer of ~4 nm AlxGayOz. The scanning transmission electron microscope (STEM)-based high-angle annular dark-field imaging (HAADF) energy-dispersive X-ray spectroscopy (EDS) mapping revelation and the depth profiles of XPS data confirm the formation of an AlxGayOz interlayer.The work of N. Manikanthababu was supported by the Department of Science and Technology (DST), India, from the Brazil, Russia, India, China and South Africa (BRICS) Project. The work of S. Lodha was supported by MeitY and DST, Government of India, through the Nanoelectronics Network for Research and Application (NNetRA) Project. The work of R. Singh was supported in part by the DST, India, under the Brazil, Russia, India, China and South Africa (BRICS) Cooperation Scheme DST/IMRCD/BRICS/Pilot Call 3/GaO-Nitrides/2019 under Grant RP04000G

Demonstration of high mobility and quantum transport in modulation-doped beta-(AlxGa1-x)(2)O-3/Ga2O3 heterostructures

In this work, we demonstrate a high mobility two-dimensional electron gas (2DEG) formed at the beta-(AlxGa1-x)(2)O-3/Ga2O3 interface through modulation doping. Shubnikov-de Haas (SdH) oscillations were observed in the modulation-doped beta-(AlxGa1-x)(2)O-3/Ga2O3 structure, indicating a high-quality electron channel formed at the heterojunction interface. The formation of the 2DEG channel was further confirmed by the weak temperature dependence of the carrier density, and the peak low temperature mobility was found to be 2790 cm(2)/Vs, which is significantly higher than that achieved in bulk-doped Beta-phase Gallium Oxide (beta-Ga2O3). The observed SdH oscillations allowed for the extraction of the electron effective mass in the (010) plane to be 0.313 +/- 0.015 m(0) and the quantum scattering time to be 0.33 ps at 3.5K. The demonstrated modulation-doped beta-(AlxGa1-x)(2)O-3/Ga2O3 structure lays the foundation for future exploration of quantum physical phenomena and semiconductor device technologies based on the beta-Ga2O3 material system. Published by AIP Publishing