Hydrogen incorporation induced metal-semiconductor transition in ZnO:H thin films sputtered at room temperature

Abstract

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.