| Research Abstract |
Since we obtained InN crystalline thin films on sapphire substrates with microwave-excited metalorganic vapor phase epitaxy, we have continued the growth of InN and InAlN,and clarified many kinds of fundamental properties. We found the experimental conditions for the single crystal films, and performed the atructural analyzes of RHEED,XRD,EPMA,XPS,AES,and X-ray rocking curve measurements. We measured the electrical properties and the optical properties in the visible and UV range.The IR reflection and the Raman effect were also measured. The summary in this study is given as follows. (1) In the heat-treated samples in vacuum and nitrogen atmosphere, the surface morphology and compositional change were observed. (2) The microhardness was measured. (3) The epitaxial relationship between the film and the substrate was determined. The crystallinity in the heat-treated samples was improved. (4) The band gap change of InN and InAlN was measured in the range of 4.2 to 300K.The III-V nitride semiconductors (InN,AlN,GaN) have smaller temperature dependence. In III-V semiconductors including the nitrides, the change is closely related the composition in the films, increasing with the atomic weight. (5) There are no reports on InAlN crystalline films. We are successful in obtaining the films with less than 14% Al content. We can control the Al content in the films. (6) The crystalline films on GaAs and GaP are obtained, and the nitrogen plasma irradiation on the surface just before the deposition is effective for obtaining the crystalline films. All the above results have been already published.
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