Widegap Semiconductor Thin Film Prepared >From Soluble Silicon Nanocluster Substituted with Organic Group

尽管传统的硅薄膜形成方法有化学气相沉积（CVD）、等离子体增强CVD等，但不稳定物质在真空室中的气相反应沉积速率有限。如果我们开发出一种利用可溶且稳定的前驱体通过液相法形成半导体薄膜的方法，将降低加工成本，提高大面积器件的制造效率，如太阳能电池和用于LCD驱动器的薄膜晶体管（TFT）。在这项研究中，我们开发了一种新的方法，通过液相工艺形成硅薄膜，使用有机可溶性硅簇作为前驱体。有机硅簇具有三维硅骨架，硅核周围的有机取代基和有机基团在普通有机溶剂中具有溶解度。将前驱体膜在真空中热处理400℃以上，消除有机取代基，制得具有非晶硅结构的无机膜。薄膜采用XeCl准分子激光退火结晶。利用拉曼光谱研究了预热和准分子激光退火对前驱体膜结构的影响。硅晶粒的大小与能量密度和激光发射次数有关。光学带隙和电学性能可以通过热处理温度和激光退火条件来控制。为了改善硅薄膜的性能，研究了以有机锗纳米团簇为前驱体制备硅锗合金的方法。激光诱导热解技术在有机锗/有机硅纳米团簇层状薄膜中的应用为制备硅锗合金提供了一种新的方法。

Although conventional methods for the formation of silicon thin films are such as chemical vapor deposition (CVD), plasma-enhanced CVD, the deposition rate by the gas-phase reaction of unstable species in a vacuum chamber is limited. If we develop a procedure to form a semiconducting thin film by the liquidphase process using a soluble and stable precursor, it would reduce the processing costs and enhance the efficiency of large-area device fabrication such as solar cell and thin film transistor (TFT) for LCD driver. In this study, we have developed a novel procedure for the formation of a silicon thin film by a liquid-phase process using an organosoluble silicon cluster as a precursor. The organosilicon cluster has a three-dimensional silicon skeleton and the organic substituents around the Si core and the organic groups bring about solubility in common organic solvents. By the heat treatment of a precursor film above 4O0℃ in vacuo, an inorganic film witht an amorphous silicon structure is prepared by the elimination of organic substituents. The film was crystallized by XeCl excimer laser annealing. The structural changes of the precursor film caused by preheating and excimer laser annealing were investigated by Raman spectroscopy. The size of the Si grain depended on the energy density and the number of the laser shot. The optical band gap and the electrical properties can be controlled by the heat treatment temperature and the laser annealing conditions. To modify the properties of the silicon film, the formation of the Si-Ge alloy using an organogermanium nanocluster as a precursor was investigated. The application of the laser-induced pyrolysis to the organogermanium/organosilicon nanocluster layered film provides a novel method to form a Si-Ge alloy.