Effect of Doping with Co and/or Sn on Crystal Structures and Properties of ZnO Thin Films
|School||Sichuan Normal University|
|Course||Condensed Matter Physics|
|Keywords||ZnO Film Sol - gel Doping Photoluminescence|
ZnO is a direct band gap semiconductor material having a hexagonal wurtzite -type crystal structure , the band gap at room temperature of 3.37eV , the exciton binding energy of about 60meV . ZnO has a good thermal conductivity , electrical conductivity , chemical stability , and good ultraviolet absorption properties, are widely used in the surface acoustic wave , UV detectors, sensors , infrared reflector , and a solar cell and other fields . It also has superior optical performance , is one of the most promising material to manufacture Blu-ray and ultraviolet light electrical parts . With the rapid development of photonics technology , more and more urgent demand for short wavelength violet and blue light-emitting materials . Because room temperature ZnO band gap of 3.37eV, coupled with its high exciton binding energy , so ZnO theoretically not only have the ability to blue and ultraviolet light emitted , even in the environment of higher than room temperature still has a significant the low the threshold excitation mechanism , further research on the the ZnO luminescence properties and its light-emitting mechanism is particularly important . In this paper, the sol - gel spin coating method prepared on glass substrates , Co, Sn -doped ZnO film series . Co and Sn -doped film surface morphology and microstructure metallurgical microscope and X-ray diffraction (XRD) . XRD results showed that the ZnO thin film samples are ( 002) preferred orientation , especially Sn doped c-axis oriented ZnO films the most significant , and grain size . XPS showed that the sample of Co and Sn valency of 2 and 4 respectively , confirmed Co 2 sup > , Sn 4 sup > into the lattice of the ZnO . Vibrating sample magnetometer (VSM) measurements indicate that Zn 1-x Co x O films have room temperature ferromagnetism . Room temperature photoluminescence (PL) spectrum displays all samples have a strong blue bimodal emission and weak green emission is also observed in pure ZnO and Co - doped ZnO thin film samples to strong UV emission peak . In addition , Co, Sn doping control can adjust the band gap of the film , thus making the blue light emission peak in the displacement has occurred ; the same time , the doping will also affect film oxygen dislocations, zinc vacancy and zinc interstitial defects , so the control the doping concentration can be modulated by the light emission characteristics of the film . Finally , we also explore the possible mechanism of light emission in different bands .