Study Of The Structure And Property Of The Cu-doped ZnO Films

ZnO is a new type of semiconductor material, following the GaN, With band gapof3.37eV and exciton binding energy as high as60meV. Its property determined itsbroad application in photoelectricity, acoustoelectricity and piezoelectricity. In recentyears, after Giant magnetoresistance was discovered, diluted magnetic semiconductors(DMSs) raised interest of scientists. Ever since Dietl et al theoretically predicted in theyear of2000that the curie temperatures (Tc) of TM doped p-type GaN and ZnO couldbe higher than room temperature, more and more research teams has started to studyoxide-based DMSs (such as ZnO). In this paper we used double target co-sputtering ofDC and RF to prepare Cu-doped thin ZnO films (ZCO), and completed the followingresearch and its conclusion as below.By the mean of magnetron sputtering, the author prepared Cu-doped ZnO films onglass substrates and studied effects of sputtering power and oxide partial pressure on thestructure and photoelectric property of the film. According to the result of x-raydiffraction (XRD) test, all doped samples has a preferential c-axis orientation. Thecrystal quality of the film tends to increase with the increase of the Cu sputtering power,and then decrease. The detection of light transmittance demonstrates while thetransmittance keeps decreasing as the Cu sputtering power increases and increasingoxide partial pressure will improve light transmittance of samples. During detection ofelectric property of samples, it is discovered that Doping Cu transforms n-type film top-type, and enriched oxygen conditions can benefit such transformations.By the mean of magnetron sputtering, the author prepared Cu-doped ZnO films onquartz substrates and studied effects on magnetism, of AZO (ZnO doped with2wt%Al2O3) buffer layers as well as annealing treatments in different atmospheres. Throughcharacterizations, it is discovered that buffer layers can improve crystal quality, but willblock generation of magnetism. Air annealing treatment reduced oxygen vacancy (VO)within the samples significantly, while weakening magnetism. Vacuum annealingtreatment preserved VOand strengthened magnetism. All samples demonstrate p-typeconductivity. Carrier concentrations of all samples are low and resistivity is relativelyhigh. Also, carrier concentrations do not have obvious effect on magnetism of thesamples. It is considered to be reasonable to explain the generation of magnetism amongthese samples with bound magnetic polaron model.