MOCVD Growth of InN using ArF Excier Laser

利用ArF激子激光的MOCVD生长技术(LA-MOCVD)是获得高质量InN薄膜的一种新的潜在方法。这种生长技术可以在从室温(RT)到非常高的温度(700sccm)的范围内进行沉积。通过在衬底表面的选定区域照射激光，在较低的生长温度下获得了选择性的InN生长。该技术在使用极少量(~100sccm)的NH3气流的情况下提供了小于0.5sccm/h的InN生长速率。成功地生长了具有良好结晶质量和良好表面形貌的单晶InN薄膜。与最近报道的良好结果相比，LA-MOCVD生长的InN薄膜的电学性能仍然很差。阐明了哪些物种是导致InN薄膜电学性能差的重要证据。为确定InN的实际带隙能量做了很好的准备。对InN带隙大小变化的原因进行了清楚的研究。发现即使在单晶薄膜的情况下，InN薄膜中的氧污染也是导致带隙吸收能值较大的原因。在低温生长的InN薄膜中，在较高温度下生长的薄膜中，氧以施主形式存在，并且由于Burstein-Moss位移而产生了较大的吸收边，这使得InN的实际光学带隙能量约为0.7 eV。

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.