| Ⅲ-nitride material system include GaN,AlN,InN and its ternary alloys InGaN, AlGaN, AlInN or quaternary alloy AlGaInN,due to its excellent physical and chemical properties in photoelectric information has a wide field of important application. The spectra measured by CL can get about material components and forbidden band width and other information; measured sample in a fixed shine wavelength can get cathode fluorescent microscopy images, contrast the SEM image of the same area, can identify the relationship of the impurities or alloy components surface morphology and space distribution of the situation in samples.By using CL, SEM,XRD, EDS,AFM we tested InGaN thin film materials which grew by MOCVD at different growth temperatures on (0001) sapphire substrates in this paper. Discussed the InGaN film, the defect and phase segregation of InGaN thin films with CL. At the same time also discussed the growth of InN films, surface morphology and optical properties. The main contents and results are as follows:1.Using CL,revealed the relationship between the growth temperature of InGaN thin films, CL wavelength and the In composition changes in the sample. With the InGaN thin film growth temperature rising, In content in the film decreases, the forbidden band increases, and CL spectrumthe peak wavelength of InGaN thin films produce a blue shift.Through the CL Mapping function, researched the luminescence of the two defects in the InGaN thin film materials, briefly discussed the generative mechanism of these two defects. Compare and analysis the SEM images and CL Mapping on the same location of InGaN thin film materials, and affirmed that the large-size V pit in InGaN film was caused from the interface defects and dislocations, directly through the GaN and InGaN two layers of material, made no contribution for the light-emitting InGaN thin film materials;the small V pits were due to the heat causes corrosion,although it has no direct contribution to light-emitting of InGaN films, but small Ⅴ-pits are in favour of light-emitting of the existence which around small V-pits in InGaN film.2.After discussed the relationship of the phase segregation and the In quantum dots in InGaN films. By CL Mapping,observed the light-emitting In enrichment quantum dots to further studied the luminous from phase segregation in InGaN thin film.We found that with growth temperature rised the luminous from phase segregation in InGaN thin films gradually became weakly and disappeared. Determine the light-emitting of InGaN thin-film is consists of InGaN material luminescence and. With different surface morphology of materials, the self-luminous and light-emitting from phase segregation have different proportion. The light-emitting of flat region is self-luminous of InGaN material, gully region shined because it was easy to accumulate of In atoms and form the phase segregation.3. Through the structure research of the InN thin films, found that the growth mode of InN thin films is by two dimensional plane turned to the island of three dimensional shape. Discusses growth time influence on film crystal quality and the surface morphology of InN thin films; Raman spectroscopy studies have shown that the preparation of InN samples plasma plasmon-LO phonon coupled mode is weak,and get the carrier concentration of InN samples by comparison and calculation. Using CL analysis system, measureed the optical properties of InN thin films at T=100k, confirmed that the InN thin film's band gap is in0.7eV nearby. |
PDF Full Text Request