MOCVD Growth of InN using ArF Excier Laser

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The MOCVD growth technique using an ArF excier laser (LA-MOCVD) has been developed as a new potential approach to obtain high qiial ity InN film.This growth technique enables deposition over a wide range of growth temperatures, ranging from room temperature (RT) to a very high temperature (700℃).Selective area growth of InN has been obtained at low growth temperature by radiating the laser beam in a selected area on the substrate surface.The technique provides a InN growth rate of wore than 0.5μm/h using a very little amount (〜100 sccm) of NH3 flow. Single crystalline InN films with good crystalline quality and excellent surface morphology have been successfully grown.The electrical properties of the LA-MOCVD grown InN films are still found to be poor compared to the recently reported good results.Important evidences as to what species is responsible for poor electrical properties in the grown InN are clarified.Effort has been made for determining the actual band gap energy of InN.The causes of the significant variation in the band gap value of InN have been clearly studied.Oxygen contamination in the InN grown film has been found to be a cause of a larger band gap absorption energy value even in the case of single crystalline film.In low temperature grown films, oxygen incorporation was significantly enhanced and seemed to exist as an alloy, which caused a larger absorption edge.Whereas, in films grown at higher temperatures, oxygen existed as a donor and caused a larger absorption edge due to a Burstein-Moss shift.This evaluation enables the conclusion that the actual optical band gap energy of InN is about 0.7 eV.