Research Of GaN Material Epitaxial Growth On PSS

Research of high quality GaN epitaxial layer grown on several different kinds of patterned sapphire substrates (PSSs) by MOCVD through a series of growing and testing experiments was developed. The influence of several growth parameters such as temperature,pressure and flux on crystal quality and morphology of epitaxial layer was also researched. Then some key process parameters were optimized and the mechanism of epitaxial growth on PSS was discussed combining with some related theories.For these different kinds of PSSs, SEM was used to characterize the morphology and XRD was used to research the crystal quality ,the surface roughness and the size of dislocation pits were investigated by AFM, also the epitaxial material of different locations of the PSS were compared with the help of chemical etching method.1,Theoretically analysis of the formative mechanism of triangle etching pits and the effect of chemical etching time on the crystal quality and surface roughness of epitaxial layer was processed, meanwhile, the etching time was optimized with the help of XRD,SEM and AFM;2,Formative mechanism of step-surface was analyzed combinee with the results of AFM, etching time was optimized on bese of crystal quality, after explanation of the effect of declining structure on epitaxial layer, growth temperature, the key parameter in epitaxial growth, was optimized;3,Growth mechanism and characteristic of GaN grown on pillar-shape PSS was discussed, the relationship betweenⅤ/Ⅲand growth rate was analyzed, following the optimization ofⅤ/Ⅲ,growth time of LT-uffer layer, regional difference existing in epitaxial layer on piller-shape PSS was qualitative analyzed with the help of chemical etching method.