AMORPHOUS INDIUM OXIDE

Ion beam sputtering of an indium metal target in the presence of oxygen can produce amorphous transparent conducting films on room temperature substrates with electrical and optical properties similar to those of polycrystalline films prepared on heated substrates. By varying the oxygen pressure we have controlled the carrier concentration in the films independently of the presence or absence of tin in the target. A detailed analysis of the electrical and optical properties of these films shows that the resistivity is dominated by ionized impurity scattering despite the amorphous structure of the films. The weak effect of the structural disorder is confirmed by studies of the interband absorption and is explained by a consideration of the relative length scales of the structural disorder and the Fermi wavelength. The fact that excellent quality films can be produced in a highly controlled process on unheated substrates implies that this process has great potential for device applications.