Preparation And Mechanism Study Of Al:ZnO/GaN/Al 2 O 3 Conductive Film

Zinc oxide is a broad band gap(3.37eV),and a larger exciton binding energy(60 meV)of the ?-? metal oxide,with outstanding optical and electrical properties,therefore,zinc oxide-based transparent conductive thin film materials can be used to prepare transparent electrodes in liquid crystal panels,solar cells,and so on.At present,ITO transparent conductive films occupy an absolute dominance in the field of transparent conductive,it is difficult to shake in a short time,but in view of Al3+doped ZnO(AZO)films have comparable properties to ITO thin films,such as good electrical performance and high transmittance of the visible area and low cost,wide resources etal,AZO thin films are the most promising alternative to ITO films and become a large number of transparent conductive film materials used in the future.Therefore,it is very valuable to experiment and simulation calculate with AZO thin films.In this paper,the structural parameters,bandgap,optical properties of AlyZni-yO(y=0,0.0625,0.125)were studied by first-principles calculations.AZO films were obtained on glass slides and GaN/Al2O3 substrates via sol-gel process and hign quality Al:ZnO/GaN/Al2O3 thin films were obtained.The effects of Al3+ doping concentration,film thickness,pretreatment temperature and annealing temperature on the films structure,surface,electrical properties and optical properties were investigated.The results show that:the structural parameters are very close to the experimental value of pure ZnO by using GGA+U method;ZnO and Al doped ZnO are direct bandgap semiconductor materials and impurity levels were introduced between Fermi levels and conduction band by doping Al leading to increasing the conduction band of the electron concentration;AlyZn1-yO(y=0,0.0625,0.125)is transparent in the visible area and the dielectric constant,refractive index and photo-conductivity are improved obviously in range of 0-3.20eV with increasing addition of Al;the optimum process parameters of the sol-gel process on the GaN/Al2O3 substrate are Al3+ concentration of 1.5 at%,20 layers,300? pretreatment,600? annealing;The XRD results show that all the films have hexagonal wurtzite structure and GaN/Al2O3 substrate crystallinity is better;XRD pattern of effects of the pretreatment temperature on the film on the glass substrate suggest that the AZO film deposited on the glass has an amorphous-polycrystalline transition temperature between 200 and 250?;the bset performence of resistivity and the square resistance of the films were obtatined on GaN/A12O3 substrate with value of resistivity and the resistance of 6.8723×10-4?·cm and 5.5624 ?/? respectively,under the optimum process.Compared to films growned on glass and ITO films,the resistivity of Al:ZnO/GaN/Al2O3 thin films was improved by at least one order of magnitude.From this point of view,Al:ZnO/GaN/Al2O3 thin films via sol gel process is expected to be applied in practice in replace of ITO.