Strong free-carrier electro-optic response of sputtered ZnO films
- Department of Basic and Applied Sciences for Engineering, SAPIENZA University of Rome, via A. Scarpa 16, 00161 Roma (Italy)
- Department of Electronic Engineering, University of Rome Tor Vergata, via del Politecnico 1, 00133 Roma (Italy)
We report on the anisotropic electro-optic response of sputtered ZnO films and its dispersion towards both the frequency of the modulating voltage and the wavelength of the probing beam. The observed dispersion put in evidence two mechanisms. A fast and weak electrorefraction response, due to the nonlinear polarization of bound electrons, and a strong and slow carrier refraction term, ascribed to the modulation of free carriers. The former corresponds to an electro-optical coefficient of approximately -0.5 pm/V, while the latter may reach a magnitude up to 20 times stronger. This term relaxes at about 12 kHz and is largely wavelength dependent, due to a combination of effects. Also bias voltages lead to its quenching, likely extending the depletion regions at grain boundaries.
- OSTI ID:
- 22089425
- Journal Information:
- Journal of Applied Physics, Vol. 112, Issue 5; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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