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Proceedings Paper

Ultrafast dynamics of Al-doped zinc oxide under optical excitation (Presentation Recording)

Paper Abstract

There is a continual need to explore new and promising dynamic materials to power next-generation switchable devices. In recent years, transparent conducting oxides have been shown to be vital materials for such systems, allowing for both optical and electrical tunability. Using a pump-probe technique, we investigate the optical tunability of CMOS-compatible, highly aluminum doped zinc oxide (AZO) thin films. The sample was pumped at 325 nm and probed with a weak beam at 1.3 μm to determine the timescale and magnitude of the changes by altering the temporal delay between the pulses with a delay line. For an incident fluence of 3.9 mJ/cm2 a change of 40% in reflection and 30% (max 6.3dB/μm modulation depth) in transmission is observed which is fully recovered within 1ps. Using a computational model, the experimental results were fitted for the given fluence allowing the recombination time and induced carrier density to be extracted. For a fluence of 3.9 mJ/cm2 the average excess carrier density within the material is 0.7×10^20cm-3 and the recombination time is 88fs. The ultrafast temporal response is the result of Auger recombination due to the extremely high carrier concentration present in our films, ~10^21 cm-3. By measuring and fitting the results at several incident fluence levels, the recombination time versus carrier density was determined and fitted with an Auger model resulting in an Auger coefficient of C = 1.03×10^20cm6/sec. Consequently, AZO is shown to be a unique, promising, and CMOS-compatible material for high performance dynamic devices in the near future.

Paper Details

Date Published: 5 October 2015
PDF: 1 pages
Proc. SPIE 9546, Active Photonic Materials VII, 95460N (5 October 2015); doi: 10.1117/12.2188175
Show Author Affiliations
Nathaniel Kinsey, Purdue Univ. (United States)
Clayton T. DeVault, Purdue Univ. (United States)
Jongbum Kim, Purdue Univ. (United States)
Marcello Ferrera, Purdue Univ. (United States)
Heriot-Watt Univ. (United Kingdom)
Alexander V. Kildishev, Purdue Univ. (United States)
Vladimir M. Shalaev, Purdue Univ. (United States)
Alexandra Boltasseva, Purdue Univ. (United States)

Published in SPIE Proceedings Vol. 9546:
Active Photonic Materials VII
Ganapathi S. Subramania; Stavroula Foteinopoulou, Editor(s)

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