MOCVD Growth of InN using ArF Excier Laser

利用ArF激振激光器（LA-MOCVD）进行MOCVD生长技术是一种有潜力获得高质量InN薄膜的新方法。这种生长技术可以在很宽的生长温度范围内沉积，从室温（RT）到非常高的温度（700℃）。在低生长温度下，通过将激光束照射到衬底表面的选定区域，实现了非晶状体的选择性区域生长。该技术使用极少量（~ 100 sccm）的NH3流量，可提供小于0.5μm/h的InN生长速率。成功地生长出了具有良好结晶质量和优异表面形貌的单晶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较差。重要的证据是什么物种是负责不良电学性质在生长的InN澄清。为确定InN的实际带隙能作了一些努力。研究了光子晶体带隙值显著变化的原因。研究发现，即使在单晶薄膜的情况下，氮化铟生长薄膜中的氧污染也是导致带隙吸收能值较大的原因。在低温生长的薄膜中，氧的掺入明显增强，并且似乎以合金的形式存在，这导致了更大的吸收边。然而，在较高温度下生长的薄膜中，氧作为供体存在，并且由于Burstein-Moss位移引起更大的吸收边。由此得出InN的实际带隙能约为0.7 eV的结论。

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.