Properties of R.F. magnetron sputtered cadmium–tin–oxide and indium–tin–oxide thin films

Abstract

The electrical, optical, structural, chemical, and etch properties of r.f. magnetron, sputter-deposited thin films of indium–tin–oxide (ITO) and cadmium–tin–oxide (CTO) are presented. Polycrystalline thin films of CTO and ITO with distinct diffraction peaks corresponding to the (220), (222), and (400) crystal planes and with an overall preferential 〈111〉 orientation were obtained at elevated deposition temperatures. The lattice parameter of these films was determined to be 0.948 and 1.026 nm for CTO and ITO, respectively. These thin films possess low resistivities in the 10 −4 Ω cm range, Hall mobilities up to 30 cm 2/V s, and carrier concentrations in the 10 20 cm −3 range. In excess of 85% of the perpendicularly incident optical radiation, in the 0.85 to 1.55 μm wavelength range, and up to 50% of the incident radiation at a wavelength of 365 nm was transmitted through the CTO and ITO conductors. A variety of wet and dry etching techniques were investigated in order to delineate features in the thin films. From investigations concerned with the Schottky and ohmic contact characteristics of CTO and ITO films deposited on undoped AlGaAs and InAlAs, ideality factors ranging from 1.1 to 1.2 and Schottky barrier heights ranging from 0.67 to 1.05 eV were obtained.