Highly Conductive, Transparent Films of Sputtered In2 − x Sn x O 3 − y

Highly conductive, transparent films of have been deposited by d‐c diode sputtering with Ar, O2, N2, Xe, and O2‐Ar mixtures. Sputtering targets with different ratios were utilized and the best results were obtained with pure Ar or Xe gas and targets containing 9–13 mole percent (m/o) . The lowest film resistivity achieved was , but routine films had resistivity values of about . The use of a very low sputtering gas throughput (10−2–10−1 Torr liter/sec) was found to be necessary to develop films with a slight oxygen deficiency. Targets differing in density (porosity) differ in their susceptibility to reduction so that sputtering conditions depend on target density. The films have excellent adherence and will tolerate cleaning, heating, polishing, and bonding without failure. They may be etched in heated acids with standard photoresist techniques used to define electrode geometry. Exposure of the films to temperatures of 500 °C in air will cause an approximate factor of 3 increase in resistance at room temperature. Sputtered films with sheet resistance of 1.6 ohms/square, 73% light transmission, and 14% reflection at 500 nm have been obtained. Suitable antireflection coated films of 5–7 ohms/square possessing over 97% light transmission appear feasible.