Preparation Of ?-Ga₂O₃ Nanostructures By Chemical Vapor Depositionand Theirdefects Luminescence Properties

Since the successful commercialization of GaN blue light emitting diodes,People pay more attention to short wavelength emerging and detection materials.In recentdecades,the direct bandgap of the wide bandgap semiconductor material??-Ga₂O₃?has attracted more and more attention.Due to?-Ga₂O₃ with a wide bandgap of 4.9 eV in the DUV region,?-Ga₂O₃ is one of the most promising candidates for DUV emission and photodetectors.However,it is not deeply enough for people to understand the emission properties of ?-Ga₂O₃.There is rare study on defects luminescence of ?-Ga₂O₃ nanostructures.The previous works show that the defect emission attributed to oxygen vacancies in the ?-Ga₂O₃ nanostructures.However,it is more than one type of oxygen vacancies in ?-Ga₂O₃ crystal structure.At present,the research on the role of each type of oxygen vacancies in the emission of ?-Ga₂O₃ is still limited,and it is necessary to further study the emission mechanism.In order to solve this problem,?-Ga₂O₃ nanowires?NWs?and nanobelts?NBs?were synthesized via chemical vapor deposition?CVD?method.We studied the different luminescence properties of NWs and NBs,and proposed the luminescence mechanism associated with the types ofoxygen vacancies.And the oxygenvacanciesemission properties of nanostructures were verified by thermal annealing and plasma treatment.The main results obtained are as follows:1.?-Ga₂O₃ nanostructures were synthesized via chemical vapor deposition?CVD?method.We control the morphology of nanostructures by controlling the flapper valve to change the furnace pressure and the size of the catalyst.We obtain the optimized NWs and NBs.The structural of ?-Ga₂O₃ nanostructures were characterized by SEM,XRD,TEM,Raman and XPS techniques.The results show NWs and NBs are monoclinic structure.And NWs has higher crystal quality than NBs.Wehas studiedthe fabrication of solar-blind photodetector with ?-Ga₂O₃ nanostructures.The test results show that the photocurrent to dark current ratio can be up to three orders of magnitude,and thedecay time is far greater than the rise time.2.By studying the CL spectra of ?-Ga₂O₃ NWs and NBs.We found NWs and NBs have strong UV-blue emission band,andNBs have wider UV-blue emission band than NWs.According to the growth mechanism of?-Ga₂O₃ NWs and NBs,we combined with the formation energyand transition levels energiesof three oxygen vacancies in?-Ga₂O₃.We found the UV and blue luminescence of ?-Ga₂O₃ NWs and NBs located at3.31 eVand 2.70 eV,mainly due to radiative recombination emission of oxygen vacancy?VO?I?and VO?II??.3.We reduced the excitation voltage in the CL test.We foundthat blue emission intensity had decreased,located at 2.70 eV.According to the different concentrationof different oxygen vacancies?VO?I?and VO?II??in NWs and NBs.We found concentration of VO?II?significantly lower than VO?I?.After air annealing and plasma treatment,the results show that the defect emission may really attribute to oxygen vacancies in ?-Ga₂O₃ nanostructures,and thatthe different oxygen vacancieshave different concentrationof in NWs and NBs.