Investigation of the Anderson transition in substoichiometric sputtered WOx by measurements of conductivity and the dielectric constant

Andreas Georg; Volker Wittwer

doi:10.1117/12.185435

9 September 1994 Investigation of the Anderson transition in substoichiometric sputtered WO_x by measurements of conductivity and the dielectric constant

Andreas Georg, Volker Wittwer

Author Affiliations +

Proceedings Volume 2255, Optical Materials Technology for Energy Efficiency and Solar Energy Conversion XIII; (1994) https://doi.org/10.1117/12.185435
Event: Optical Materials Technology for Energy Efficiency and Solar Energy Conversion XIII, 1994, Freiburg, Germany

Abstract

Thin substoichiometric WO_x films were produced by reactive sputtering with variation of the oxygen partial pressure and the temperature of the substrate to get samples with different degrees of crystallinity and colorations. Measurements were done on the conductivity, the transmittance and reflectance from 100 K up to 300 K. The dielectric constant was evaluated by ellipsometry. As observed in earlier works, with increasing coloration a sudden increase in conductivity and a decrease of the temperature dependence of the conductivity takes place, which is attributed to an Anderson transition. But based on Hall measurements and the ellipsometrically evaluated dielectric constants the formation of Drude electrons with a plasma edge in the visible or NIR range is unlikely. Rather the measured dielectric constant suggests a strong Lorentz oscillator with a weak bond of the coloring electrons. Reflectance and transmittance did not change when cooling the samples from 300 K to 100 K. At very high colorations a second qualitative change of the conductivity and the optical properties was observed. Here perhaps the first metallic clusters are formed.

Citation Download Citation

Andreas Georg and Volker Wittwer "Investigation of the Anderson transition in substoichiometric sputtered WO_x by measurements of conductivity and the dielectric constant", Proc. SPIE 2255, Optical Materials Technology for Energy Efficiency and Solar Energy Conversion XIII, (9 September 1994); https://doi.org/10.1117/12.185435

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available