Study On The Synthesis Of Ga/Sc Co-doped Zinc Oxide Crystal By Hydrothermal Method And Its Optical Properties

Zinc Oxide?ZnO?is a semiconductor material with a band gap of 3.37eV.Because of its high exciton binding energy?60Mev?at room temperature,it is stable at room temperature and is not easy to excite.As an excellent inorganic material,ZnO has been widely applied to the field of optoelectronics.However,ZnO materials usually have intrinsic defects and polar growth characteristics.In order to improve the application of ZnO in high-end field,researchers have studied on doping modification by different methods.The most common use is the elements of group?A,such as Al,Ga,In and so on.The doping of group?A can significantly change the characteristics of ZnO,so that it can be applied to new fields.In the elements of group?A doped system,Ga doping is proved to be effective n type doping.Gallium doped Zinc Oxide crystals also exist polar growth problem to be solved.In order to improve the quality and size of crystals,Ga/Sc co-doped Zinc Oxide crystals were prepared by hydrothermal method with high purity ZnO ceramics as main nutrients and Ga₂O₃ and Sc₂O₃ as precursors.The experiment mainly includes the research of the growth process by hydrothermal method and test of ZnO single crystal.The growth conditions include 4 mol/L KOH+0.25mol/L LiOH as mineralizer,reaction temperature of 380?,and the fill factor of 75%,the experimental period is 30days.Studying on the relationship between growth habit and the doping of pure ZnO,ZnO:Sc,ZnO:Ga and ZnO:Ga_xSc_y crystals grown by hydrothermal method.The growth defects and optical properties of ZnO:Ga_xSc_y single crystals and the influence of dopants on their optical properties are tested and analyzed.The results show that the growth of the Ga/Sc Co-doped ZnO crystal has a shape of hexagonal prism;the surface of the whole crystal is smooth.The negative pole-c?000^—1?large area exposure,a negative pole?000^—1?and m?10^—10?growth rate significantly increased,forming a three-dimensional growth.The morphology of ZnO crystal has a great change after co-doping..C-SAM observation shows there are a certain number of growth defects in the crystals,but it is significantly less than the gallium doped ZnO crystal under the same conditions.The X-ray rocking curves FWHM for?0002?of Ga/Sc co-doped ZnO crystals is 28aresec,and 46aresec for?000?2?,indicating the crystals had high crystalline quality.The reason why the quality of+c surface is better can be attributed to the faster growth of+c direction,the-c surface is the oxygen surface,and there are many oxygen vacancies,so it is easy to adsorb the metal cation impurities in the solution.In the other hand,UV/VIS/NIR spectroscopy showed the transmittance of Ga/Sc co-doped ZnO crystals were between the scandium-doped ZnO crystals and the gallium-doped ZnO crystals.It shows that the optical band gap of Ga/Sc co-doped ZnO crystals were between the scandium-doped ZnO crystals and the gallium-doped ZnO crystals,Ga/Sc co-doped doping maybe leads to the widening of optical band gap in the visible light region of ZnO crystal.Laser Raman spectroscopy shows that the doped ZnO crystals appear sharp essential characteristic peaks at about 437 cm^-1,indicating that it is still has a structure of wurtzite,and the defects of the crystals are less and the crystallinity is relatively high,which is basically consistent with the above X-ray rocking curves.Doping can cause lattice distortion to decrease symmetry,and the subtle change of crystal structure will lead to the migration and variation of Raman peaks,its characteristic peaks moving at low frequency finally.The additional vibration mode of 632 cm^-11 position may be due to the ZnO intrinsic defect caused by a specific doping atom.