Electrical and optical properties of copper‐based chalcogenide thin films deposited by pulsed laser deposition at room temperature: Toward p‐channel thin film transistor fabricable at room temperature

Abstract

AbstractCopper‐based chalcogenide thin films deposited at room temperature were examined for exploring an active layer material for a p‐channel thin film transistor (TFT) fabricable at room temperature. The electrical conductivities of chalcopyrite and simple copper chalcogenide thin films were controlled by introducing hydrogen sulfide and oxygen gases, respectively, during the film deposition. However, no current modulation by gate bias was observed in fabricated TFTs. Optical absorption spectra showed intense subgap absorptions, and these subgap states are thought to pin the Fermi levels. Although these copper‐based chalcogenides did not work as TFT channels, we found that simple copper chalcogenides deposited under a high vacuum showed p‐type degenerate conduction with a high conductivity up to 7.3 × 103 S/cm and a reasonably large work function of ∼4.7 eV. These properties are rather favorable for a hole injection layer of flexible electronic devices and suggest a promising application as an anode layer in organic light emitting devices. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)