Study On Aluminum-doped Zinc Oxide (AZO) Thin Films And Photovoltaic Properties

Al-doped zinc oxide (AZO) thin film is one kind of wide band gap semiconductor materials. It has high transmittance for the visible light and high absorption for ultraviolet. And it has many realized and potential applications such as surface acoustic wave devices, ultraviolet photodetectors, piezoelectric devices, varistors, ete.In this paper, Zn1-xAlxO (AZO, x=0,0.01,0.02,0.03) thin films were prepared by sol-gel and PLD method. The AZO films were prepared by sol-gel method, using2-methoxyethanol as solvent, zinc acetate as precursor and ethanol amine (DEA) as stabilizer, which include heat treatment and spin coat process. The film has been prepared by PLD on the Si (111) substrate, and the influences of substrate temperature, growth pressure, deposition time and Al-doping on the structure of AZO films were also investigated.The microstructure and properties of samples were characterized by means of SEM, XRD, PL spectrum, Ultraviolet-Visible Absorption Spectroscopy (UV-vis), Atomic Force Microscope (AFM) and R-T et al. The contents of this dissertation are listed as follows:1. The results of XRD indicate that the AZO films have highly (002) preferred orientation prepared by sol-gel. Experimental results show that the films with coating layer number of10present low resistance and high transmittance. After annealed at500℃, the transmittance in visible wavelengths of films is best, followed by400℃-600℃. When the molar ratio of Al to ZnO is1.0%, the films present excellent properties, with low surface resistance, relatively high density and transmittance, blue shift of cutoff wavelength and absorption edge of transmission light. The A.ZO film has been prepared by sol-gel under the following optimized conditions:the coating layer of15, the annealing temperature of500℃and the Al doping of1.0at.%.2. The transparent AZO film has been prepared by sol-gel method, with the transmittance of87%in visible light and the resistance of4.2×10-2Ω·cm.3. The result of XRD shows that the AZO films grow along the c axis and present well-crystallized The AZO films have been prepared by PLD under the following optimized conditions:the substrate temperature of600℃, the growth pressure of0.5Pa, the deposition time of10min and the Al doping of1.0at.%.The influences of substrate temperature and Al-doping on the surface morphology of AZO films were investigated by AFM. The results indicate that when the temperature of substrate is600℃, the property of prepared AZO films is best, with relatively high density and uniform grains. Compared with pure ZnO films, the grain of AZO films has high uniformity and low surface roughness. Within the range of experiment, Al doping amount hasn’t significant effect on the surface morphology of AZO films.4. The results of PL spectrum show that all of the substrate temperature, growth pressure, deposition time and Al-doping have greater impact on the Ultraviolet luminescence properties of AZO films. The results of R-T of AZO film prepared by optimized conditions show that when lower temperature to a certain extent, resistance will increase rapidly, which maybe relate to impurity promote conduction of the oxygen vacancy.