Fabrication And Optimization Of Mg-doped ZnO Films

As an excellent representative of the 3rd generation semiconductor materials,ZnO owns a wide band gap of 3.37 eV at room temperature and a large exaction binding energy of 60 meV.The photoluminescent range contains the entire area from ultraviolet to infrared light wavelength,and the transparency could reach as high as 90%.Meanwhile,it also has advantages of abundant and inexpensive.And synthetic conditions of high-quality ZnO thin films could be acquired at a relatively low growth temperature,all of which make ZnO a priority material in the future photoelectric field.However,in order to achieve the wide application of ZnO in the photoelectric field,the key is to obtain the ZnO thin film with excellent quality,and then reach the goal to acquire ZnO-based devices with excellent performance.Mg2+has similar advantages,such as similar ionic radius to Zn2+,Mg-O bond energy are more strong and high Vo formation energy in MgO.At present,there are few studies on Mg-doped ZnO thin films(MZO),and the preparation methods mainly focus on physical methods.Nevertheless,these methods have disadvantages,such as expensive equipment,high cost,complicated operation and high requirement for vacuum.Therefore,based on the above situations,in this work,MZO films were prepared by sol-gel method and chemical bath deposition method(CBD method),and a series of experimental parameters such as reaction time,reaction temperature,pH,ZnO seed layer and solution were investigated by means of XRD,SEM,EDS,EPMA and AFM.The main research contents and results are as follows:Under the experimental conditions of typical CBD method,when the reaction time was 4 h and the growth temperature was 90?,MZO films owned an optimal crystallinity.When the pH value of chemical bath precursor was about 7,the non-polarity of MZO films can be maintained,and the crystallinity is better.The addition of Mg2+ into the seed layer promoted the preferred orientation of the thin films be prepared by chemical bath deposition method to change to the non-polar direction.When the magnesium source changed,the concentration of citric acid was 0.50 mM and the doping of Mg2+was 3%,the mass percentage and atomic percentage of Mg2+in the thin films were 0.70 wt%and 0.96 at%,respectively.The crystallinity of the MZO films reached the optimum under these experimental conditions,that was the volume of dimethyl sulfoxide were 1 mL and the doping amount of Mg2+were 1%;the volume ratio of diethylene glycol to the reaction solution was 1:51,the water bath temperature was 100? and the water bath time was 4 h;the acid concentration was 0.05 mM,0.15 mM,and 0.50 mM,and the Mg2+ doping amount was 1%.When the dopant is Mg(NO3)2·6H2O,and the doping amount of Mg2+ was 1%,the MZO film owned an optimal crystallinity.At the same time,the roughness of MZO film was optimized.