Electronic excitation-induced tunneling and charge-trapping explored by in situ electrical characterization in Ni/HfO2/β-Ga2O3 metal–oxide–semiconductor capacitors

• Published in: Materials science & engineering. B, Solid-state materials for advanced technology Solid-state materials for advanced technology, 2022-07, Vol.281, p.115716, Article 115716
• Main Authors: Manikanthababu, N., Tak, B.R., Prajna, K., Sarkar, S., Meena, R.C., Asokan, K., Barman, S.R., Singh, R., Panigrahi, B.K.
• Format: Article
• Language: English
• Subjects: Capacitance-voltage characteristics; Charge-trapping; Electrical properties; Energy levels; Excitation; Gallium oxides; Hafnium oxide; Heavy ions; In situ I-V and C-V characteristics; Metal oxide semiconductors; Photoelectrons; Swift heavy ion (SHI) irradiation; Tunneling; β-Ga2O3; β-Ga2O3/HfO2 MOSCAPs
• ISSN: 0921-5107; 1873-4944
• DOI: 10.1016/j.mseb.2022.115716

•Annealing and creation of defects from PF emission is vital in Ni/HfO2/Ga2O3 device.•Enhanced barrier height from Schottky emission is via annihilation of defects.•The significant changes in trapped charges reveal the role of electronic excitation.•X-ray Photoelectron Spectroscopy suggests that there is an increase of O vacancies. In situ current–voltage and capacitance–voltage characteristics were performed on Ni/HfO2/β-Ga2O3 devices using 120 MeV Ag7+ swift heavy ion (SHI) irradiation. The Poole-Frenkel emission is significant within 2.25–7.50 MV/cm until 5 × 1012 ions/cm2 and covers a full range of 0.01–7.50 MV/cm for the fluences of 1 × 1013 and 5 × 1013 ions/cm2 under gate injection. The estimated trap energy level is Ec − 0.73 eV for pristine device whereas Ec − 0.65 eV is for 5 × 1013 ions/cm2. Ni/HfO2 BH is 0.88 eV for the pristine device from Schottky emission. It is found to improve to 1.04 eV until 5 × 1012 ions/cm2 and then decrease to 0.75 eV at 5 × 1013 ions/cm2 due to the athermal annealing. From Fowler-Nordheim tunneling, the BH of Ni/HfO2 interface is 0.78 eV and 0.69 eV at 1 × 1013 ions/cm2 and 5 × 1013 ions/cm2. X-ray photoelectron spectroscopy at O 1s reveals an increase in O defects within HfO2 due to electronic excitation.