Preparation And Characterization Of P-type CuAlO₂ Films

CuAlO2 is a novelⅠ-Ⅲ-Ⅵcompound semiconductor with a indirect bandgap. It is transparent in the visible spectral range with a direct optical bandgap of about 3.5 eV, and the first discovered Cu-based p-type semiconductor. It has a lot of potential applications in optoelectronic devices because of its unique properties. The discovery of p-type transparent conducting oxide (TCO) made possible the fabrication of transparent oxide optoelectronic devices, such as transparent p-n junction diodes and transistors using an appropriate combination of p-and n-type TCO films, which also led TCO materials to the frontier of transparent oxide semiconductor (TOS). This thesis is aimed at fabricating p-type CuA102 films on quartz and sapphire substrates using rf magnetron sputtering. We studied the structural, electrical and optical properties. The main results are listed as follows:First of all, because the as-grown films prepared by rf magnetron sputtering were non-crystalline, we applied the annealing technique to the Cu-Al-O film and successfully achieved CuA102 crystalline films with the (001) orientation. For the annealed CuAlO2 films, the transmittance was around 60% in the visible range.Second, we systematically studied the effect of the growth parameters on the CuAlO2 films. The substrate temperature, sputtering power and sputtering time had a great impact on the structural, electrical and optical properties. When the substrate temperature is lower than 300℃, sputtering power is larger than 200W and the growth time is less than 2 hours, the film shows the c-axis orientation with dense film and smooth surface. When the substrate temperature is higher than 400℃, sputtering power is smaller than 120W and the growth time is more than 3 hours, the film orientation was changed to (110) orientation with poor quality and micro-holes in the surface.Finally, we focused on the photoluminescence (PL) properties of the CuAlO2 films grown by magnetron sputtering and PLD technique. We first analyzed the defect emissions in PL spectra and draw the conclusion that the defect level of copper is about 0.82eV.