Preparation Of Al, N Doped ZnO Thin Films And The First-Principles Calculation Of ZnO

Transparent-conductive zinc oxide(ZnO) thin films have been given considerable attention due to their significant potential in the applications of photonic devices, transparent conducting electrodes and thin film solar cells. Al and N doped ZnO thin films were prepared by AACVD method and calculated by first-principles calculations. The structure, morphology, optical and electrical properties were investigated by X-ray diffractometer, atomic force microscope, SEM, UV-vis double beam spectrophotometer and 4 point probe method.The results showed that all the sample were ZnO hexagonal wurtzite type with high purity which deposited by AACVD. Precursor solution volume had no impact on the crystal orientation and crystallinity, but it would significantly affect the morphology and the electro-optical properties of AZO thin films. The films had the best performance when the precursor solution volume was 35 ml. And the sheet resistance was only 1.63 K?/□, the transmittance was 88.53%. Excellent performance of films with different precursor solution could be combined together by dual-source AACVD method. The AZO films with higher transmission and also low resistance could be prepared. When the precursor solution was 15 ml ethanol and 20 ml methanol,the AZO thin film had best electro-optical performance and the quality factor was 5.64×10-4. Surface morphology of the films were also heavily dependent on the ratio of ethanol and methanol in the precursor solution. The properties of the films could be improved by the intermittent atomization. When the time of atomization was constant, the film has best performance with the time of atomization interval was 4 min, but when the time of atomization interval kept unchanged the film deposited with 8min of atomization time had best performance.The best ratio of Zn and N was 1:0.5 when the N doped ZnO thin film. Comparing with the Al and N single-doped ZnO films, the co-doped ZnO film had better performance. Effect of the temperature on the performance of Al-N co-doped film is very obvious, especially in the optical properties and morphology. When the temperature is 350 ℃, the transmittance of the film was only 65.7%, the film prepared the best property when the substrate temperature was 400 ℃. By the first-principles calculation, when the N atom substituted O atom and Al-N co-doping, ZnO exhibited p-type conductivity, but when the N atom substituted Zn atom the ZnO exhibited n-type conductivity. The formation energy were different when the doping way were different and the Al-doped and Al-N co-doped ZnO had low formation energy. Defects can significantly affect electronic structure and optical properties of the Al-N co-doped ZnO and the formation energy was minimum when there was Oi defects in ZnO.