Characterization of sputtered amorphous platinum dioxide films

Amorphous platinum dioxide, a-PtO₂, films are formed commonly during reactive sputtering of platinum at relatively high power density levels and high oxygen partial pressures. The structure of a-PtO₂ is intermediate between the crystalline alpha and beta phases of this compound and either phase may form upon annealing or by lowering the power density during sputtering. Amorphous platinum dioxide is a semiconductor, and its resistivity depends on deposition parameters. Films of a-PtO₂ are dense, chemically resistant, smooth, reflective, and have a hardness similar to titanium nitride. The films may be reduced in hydrogen at room temperature or in carbon monoxide at 200°C to produce metallic platinum with crystallite sizes in the range of 5-10 nm. Any of these properties may be exploited to produce films that could be used in the development of sensors, optical materials, and in microelectronics.