The leakage current and reliability characteristics of γ-ray-irradiated sputtered titanium dioxide (TiO2) thin films have been systematically investigated. Analytical results revealed that the inferior polycrystallinity and the larger leakage current of the anatase structure of unirradiated TiO2 thin film could be effectively improved by raising the irradiation dose at low γ-ray doses [≦10 kGy(TiO2)]. However, any higher dose [>10 kGy(TiO2)] causes undesirable deterioration of the film crystallinity, yielding an increased leakage current. The optimal dose of γ-rays [10 kGy(TiO2) in this work] not only provides a proper energy transfer to the TiO2 film, but also reduces the oxygen deficiency and/or Si-diffusion contamination, resulting in a superior crystallinity, and thus causing the reduced leakage current. The excellent agreement between the E model (thermochemical-breakdown model) and the time-dependent-dielectric-breakdown data suggested strongly that the best long-term reliability of metal–oxide–semiconductor capacitors with the TiO2 gate oxide treated by 10 kGy(TiO2) of γ rays was due to the superior crystallinity and the smaller hole trap density at the TiO2/Si interface, resulting in an increased activation energy, thus reducing the occurrence of breakdown.
Effects of gamma-ray irradiation on the microstructural and luminescent properties of radio-frequency magnetron-sputtered GaN thin filmsThe microstructural and luminescent properties of pre-irradiated and neutron-irradiated sputtered GaN thin films were systematically investigated. Analytical results revealed that the optimal (1 ϫ10 13 n/cm 2 ) neutron irradiation fluence could not only promote the crystallinity of GaN thin films, but also effectively repress the occurrence of deep level luminescence in the photoluminescence spectrum due to the creation of nitrogen-related deep electron traps (E t1 ). Moreover, from both the Fourier transform infrared spectroscopy and yellow band emission results, it is strongly suggested that Ga-H complexes in the vicinity of the nitrogen vacancy, forming the E t2 trap, possibly act as the origin of yellow band emission in GaN material. The superior I -V characteristics resulting from the optimal (1ϫ10 13 n/cm 2 ) neutron irradiation fluence on the Au/sputtered GaN Schottky diode were attributed mainly to the superior crystallinity, creating the fewer deep electron traps of E t1 , leading to a smaller turn-on voltage as well as a larger conduction current in the forward-biased situation. In the reverse-biased condition, the smaller leakage current and the larger breakdown voltage were suggested to probably be due to the presence of fewer nitrogen vacancies and/or less Ga-Au compound formation at the Au/GaN junction.
The microstructural and luminescent properties of sputtered GaN thin films preiiradiated and γ-ray irradiated were systematically investigated. Analytical results revealed that the increasing doses of γ rays could enhance the occurrence of more nitrogen vacancies, which not only created a prominent deep level luminescence but also destroyed the crystallinity of GaN thin films. For low dose of γ-ray irradiation [≦4 Mrad (GaN)], evidence showed that by raising the irradiation dose, more associated Ga–H complexes would be effectively promoted, yielding an enhanced yellow band emission. However, for high dose of γ-ray irradiation [>4 Mrad (GaN)], further higher doses of γ rays could lead to the dissociation of Ga–H complexes in GaN samples, resulting in a repressed yellow band emission. From both the Fourier transform infrared spectroscopy and yellow band emission results, it is strongly suggested that Ga–H complexes in the vicinity of N most probably act as the origin of yellow band emission in GaN material.
The structural and optical properties of rf magnetron-sputtered GaN thin films on p ϩ -Si substrates have been accessed as a function of rapid thermal annealing ͑RTA͒ temperatures from 800 to 1000°C. The evidence has revealed that higher RTA temperatures not only assist the GaN films in recrystallizing into stable hexagonal form but also enhance the near-band-edge emission of GaN films in the photoluminescence spectrum. Moreover, a deep electron trap (E t ) with activation energy E c ϪE t Х0.39 eV detected at the surface of higher-RTA-temperature-treated GaN films was asserted to be a nitrogen-vacancy-related defect that takes a defect-assisted-tunneling role in the forward conduction process of Au/GaN Schottky diode. The greater reverse leakage current and lower breakdown voltage are suggested to be due to the effects of a lower barrier height and higher ideality factor that occurred in the higher-RTA-temperature-treated samples.
The electrical conduction mechanisms and reliability characteristics of rf-sputtered TiO2 thin films deposited at different temperatures have been systematically investigated. Analytical results revealed that adequate sputtering temperature not only provided a superior polycrystallized TiO2 film as well as a less leakage current, but also reduced the oxygen vacancy, resulting in the Frenkel–Poole (FP) conduction mechanism of low-temperature (400–500 °C) sputtered samples transiting to the Schottky emission (SE) process of medium-temperature (600–700 °C) sputtered samples. However, for samples sputtered by higher temperature (750–800 °C), the evident oxygen deficiency due to the deteriorated crystallinity and significant Si diffusion contamination in the TiO2 films were asserted to be the two main causes leading to the SE conduction process in medium-temperature (600–700 °C) sputtered samples transiting to the FP conduction mechanism in high-temperature (750–800 °C) sputtered samples again. Besides, the excellent agreement between the E model and the time-dependent-dielectric-breakdown data suggested strongly that the exhibited best long-term reliability of metal–oxide–semiconductor capacitors with TiO2 gate oxide sputtered at 700 °C was due to the possession of superior crystallinity and less interface hole trap density at the junction of TiO2/Si, resulting in a higher thermal activation energy Ea of 0.709 eV at 5 MV/cm, reducing the breakdown occurrence.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.