Preparation of CuAlO2 nanocrystalline transparent thin films with high conductivity

P-type transparent CuAlO2 semiconductor films are made by the spin-on technique from nanocrystals. The nanocrystals are synthesized by a hydrothermal metathesis reaction. Scanning electron microscopy, x-ray diffraction and energy dispersive x-ray spectrometry suggest that the films contain nanocrystalline phases of CuAlO2. Both the Hall technique and Seebeck measurements reveal that the film is p-type and a very high room-temperature conductivity of 2.4 S cm(-1) is achieved. This success in fabricating a high-conductivity transparent CuAlO2 film indicates that nanotechnology will be helpful in enhancing the conductivity of p-type transparent semiconductors. The Hall measurement of the film shows a sheet mobility of 3.6 cm(2) V-1 S-1 and a carrier concentration of 5.4 x 10(18) cm(-3). The optical band-gap of the film is estimated to be 3.75 eV and the activation energy for the positive hole is 0.14 eV.