Optical properties of oxygen vacancies in HfO 2 thin films studied by absorption and luminescence spectroscopy
Hafnium oxide thin films with varying oxygen content were investigated with the goal of finding the optical signature of oxygen vacancies in the film structure. It was found that a reduction of oxygen content in the film leads to changes in both, structural and optical characteristics. Optical absor...
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Published in | Optics express Vol. 26; no. 13; p. 17608 |
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Main Authors | , , , , , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
United States
Optical Society of America (OSA)
25.06.2018
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Subjects | |
Online Access | Get full text |
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Summary: | Hafnium oxide thin films with varying oxygen content were investigated with the goal of finding the optical signature of oxygen vacancies in the film structure. It was found that a reduction of oxygen content in the film leads to changes in both, structural and optical characteristics. Optical absorption spectroscopy, using nanoKelvin calorimetry, revealed an enhanced absorption in the near-ultraviolet (near-UV) and visible wavelength ranges for films with reduced oxygen content, which was attributed to mid-gap electronic states of oxygen vacancies. Absorption in the near-infrared was found to originate from structural defects other than oxygen vacancy. Luminescence generated by continuous-wave 355-nm laser excitation in e-beam films showed significant changes in the spectral profile with oxygen reduction and new band formation linked to oxygen vacancies. The luminescence from oxygen-vacancy states was found to have microsecond-scale lifetimes when compared with nanosecond-scale lifetimes of luminescence attributed to other structural film defects. Laser-damage testing using ultraviolet nanosecond and infrared femtosecond pulses showed a reduction of the damage threshold with increasing number of oxygen vacancies in hafnium oxide films. |
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Bibliography: | NA0001944 New York State Energy Research and Development Authority 2017-239; 2-370 USDOE National Nuclear Security Administration (NNSA) Univ. of Rochester, NY (United States) |
ISSN: | 1094-4087 1094-4087 |
DOI: | 10.1364/OE.26.017608 |