The room temperature deposited ZnO:H thin films having high conductivity of 500 Ω−1 cm−1 and carrier concentration reaching 1.23 × 1020 cm−3 were reactively sputter deposited on glass substrates in the presence of O2 and 5% H2 in Ar. A metal-semiconductor transition at 165 K is induced by the increasing hydrogen incorporation in the films. Hydrogen forms shallow donor complex with activation energy of ∼10–20 meV at oxygen vacancies (VO) leading to increase in carrier concentration. Hydrogen also passivates VO and VZn causing ∼4 times enhancement of mobility to 25.4 cm2/V s. These films have potential for use in transparent flexible electronics.
Received 03 April 2013Accepted 16 April 2013Published online 30 April 2013
One of the authors (A.S.) acknowledges CSIR, New Delhi for Senior Research Fellowship. We also thankfully acknowledge the help and discussions with Dr. R.P. Pant, N.P.L. New Delhi for EPR studies and Prof. S. Major, I.I.T. Bombay for XPS studies.