Chalcogen-based transparent conductors

Chalcogenide-oxides and chalcogenide-fluorides exhibit p-type conductivity and transparency, and in many cases, these properties exist simultaneously. We present the properties of several of these materials, BaCuQF (Q = S, Se, Te), BiCuOSe, and Cu3TaS4. BiCuOSe is a low band gap degenerate semiconductor with a high conductivity, and oriented films can be easily prepared. We show that epitaxial thin films of BaCuTeF and highly c-axis oriented films of BaCuSeF can be prepared by pulsed laser deposition on MgO substrates. Undoped BaCuTeF thin films exhibit a maximum conductivity of 167 S/cm, mobility of 8 cm2/Vs and band gap of 3 eV, while the selenide and sulfide versions are progressively less conducting and exhibit lower mobility. Strong excitonic features are observed in BaCuSeF and BaCuSF. Cu3TaQ4 powders and films have been prepared and these show p-type conductivity, with absorption onsets in the range 2.8–3.0 eV.