In situ electrical characteristics and defect dynamics induced by swift heavy ion irradiation in Pt/PtOₓ/β-Ga₂O₃vertical Schottky barrier diodes

In situ I – V and C – V measurements were performed on Pt/PtOx/ β -Ga2O3 vertical Schottky barrier diodes (SBD) during 120 MeV Au9+ swift heavy ion (SHI) irradiation in a fluence range of 1×1010 – 2×1012 ions/cm2. The reverse leakage current density increased from 1.21×10−10 to 1.69×10−4 A/cm2 at −1 V. The Schottky barrier height (SBH) remains close to ~1.8 eV up to the fluence of 5×1011 ions/cm2, and however, at the fluences of 1×1012 and 2×1012 ions/cm2, the SBH increased to 1.93 and 2.03 eV, respectively. Also, the ideality factor (IF) increased from 1.07 to 1.38. The in situ C – V measurements showed a similar trend, as the SBH decreased from 2.04 to ~1.88 eV until 5×1011 ions/cm2, but it increased to 2.14 and 2.56 eV at 1×1012 and 2×1012 ions/cm2, respectively. In addition, the doping concentration decreased from 1.01×1016 to 0.27×1016 cm −3 as the defects increased significantly at the fluence of 2×1012 ions/cm2. The cathodoluminescence measurements revealed various Ga and O defects produced during SHI irradiation. Cross-sectional transmission electron microscopy measurements confirmed the formation of tracks within β -Ga2O3 along the SHI path, and these results are explained with the inelastic thermal spike model.The work of N. Manikanthababu was supported by the Department of Science and Technology (DST), India, through the Brazil, Russia, India, China, and South Africa (BRICS) Project. The work of R. Singh was supported in part by DST, India, through the BRICS Cooperation Scheme DST/IMRCD/BRICS/Pilot Call 3/GaO-Nitrides/2019, under Project RP04000G

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