Controllable Preparation And Performance Studies Of Porous Gallium Nitride Semiconductor Materials

In this thesis,the purpose of graphical controlled etching of gallium nitride?GaN?was realized,that was epitaxially grown on the sapphire substrate,using photoelectrochemical wet etching,photochemical wet etching,ball template method,and techniques of semiconductor materials such as stoving,spin-coating,Czochralski,evaporation and deposition.In addition,the advantage of III-V semiconductor materials realized the applications of photoluminescence,photocurrent response and surface-enhanced Raman scattering.The main contents of this thesis included the following three aspects:1.Through photo-assisted electrochemical etching method,and ionic liquid as etching agent,pore structure and surface roughness of GaN appeared via using 300W xenon lamp as illuminant.The influence of different anionic group on morphologies was discussed using 1-ethyl-3-methylimidazolium trifluoromethanesulfonate,1-ethyl-3-methylimidazoliumbis??trifluoromethyl?sulfonyl?imide,1-ethyl-3-methylimidazolium trifluoroacetate,and the influence of different cationic group was analysed using 1-ethyl-3-methylimidazolium trifluoromethanesulfonate,1-butyl-3-methylimidazoliumtrifluoromethanesulfonate,1-octyl-3-methylimidazolium trifluoromethanesulfonate.Subsequently,I selected1-ethyl-3-methylimidazolium trifluoromethanesulfonate as etchant to design experiments to get optimum etching voltage and etching time,and characterize and analyze their lattice structure and chemical bonds.2.In this work,author use copper-mesh?aperture of 35?m and 6.5?m?as mask,with method of photo-assisted electrochemical etching,realizing graphical controlled etching of GaN with regular lattice pattern on the surface.Size of lattice can be decreased from 35?m to 6.5?m.Moreover,30nm thick graphical gold film was evaporated on the surface of etched GaN,and prepared micron-scale surface graphics by photoelectrochemical etching.Then I used the methods of stoving,spin-coating and Czochralski to prepare self-assembled monolayer film of SiO₂ spheres.And ball template wet etching was carried out.3.The photoluminescence performance of porous GaN used different ionic liquid as etchants were measured.I assessed the intensity of the photoluminescence at different etching times and measured photocurrent response of porous GaN.Finally,Ag nanoparticles/porous GaN composite were deposited by electrochemical method,and used to detect trace Rhodamine 6G?R6G?molecule.It is obvious that the porous GaN is a new candidate of substrate material of surface-enhanced Raman scattering due to its good repeatability and high enhancement factor.