Optimization of Photon-Assisted Microwave CVD with Application to Thin Film Transistors and Solar Cells

非晶硅(a-Si)和微晶硅(MC-Si)是用于平板显示器和光伏(PV)的薄膜晶体管(TFT)的重要技术材料。这两种材料在受光照射或外加电压时都容易降解。这种不稳定性导致了非最佳的器件性能，即使已知存在部分稳定材料的方法。这项研究将试图通过引入特殊的加工技术来改善这些不稳定性。改进后的a-Si和MC-Si将用于TFT和PV器件的制造。微波电子回旋共振(MECR)将用于沉积，并在沉积过程中通过照明衬底来提高长期稳定性。进一步提高器件稳定性的工艺步骤将包括氢稀释和特殊掺杂剂。在初步意义上，国际和平研究所探索了这些方法，取得了令人鼓舞的结果。钛掺杂剂的使用增加了光电导性，而不增加暗电导率，从而改善了比率。在MECR(称为PAMECR)过程中用强光照射衬底提供了一种材料，该材料在以后暴露在光下时具有极大的稳定性，并极大地改善了电性能。光子辅助的使用使a-Si中的载流子寿命增加了十倍，而MC-Si中的晶体直径增加了一倍。使用这种稳定的材料将产生稳定的器件。将深入研究H稀释的PA-MECR和各种掺杂剂，以生产更稳定的a-Si和MC-Si，用于TFT和光伏器件。现场闭合离子源质谱(CIS-MS)将用于将工艺气体的组成与工艺条件的变化相关联。薄膜将通过各种技术进行评估，包括FTIK、AFM、TEM、SIMS、AES、XPS等。器件将使用最好的材料制造并进行长期稳定性测试。使用稳定的薄膜硅可以减少TFT的电压不稳定性，减少光伏器件的光致不稳定性。将在低成本的基板上使用特殊的缓冲层，以允许以合理的成本制造大面积器件。布鲁克海文国家实验室的SUNY光束线将被用来探索掠入射X射线散射(GIXS)层间的微观界面粗糙度及其与电性能的关系。因此，主要目标将是开发改进的MC-Si和ASI，并了解PA工艺的作用，使用CIS-MS、FTIR、GIXS和其他技术来建立最佳的沉积工艺。等离子体化学将与a-Si中的成键信息和MC-Si中的氢钝化有关，这些信息与电学性质、光学性质和稳定性有关。

9902437AndersonAmorphous silicon ( a-Si ) and Microcrystalline silicon (mc-Si) are technologically important materials for thin film transistors ( TFT's ) used in flat panel displays and for photovoltaics ( PV ). Both materials are prone to degradation when subjected to light exposure or applied voltages. This instability leads to non-optimum device performance, even though methods of partially stabilizing the material are known to exist. This study will seek to improve upon these instabilities by introducing special processing techniques. The improved a-Si and mc-Si will be used in fabrication of TFT's and PV devices.Microwave electron cyclotron resonance ( MECR), proven to produce more stable materials, will be used for deposition, with an assist by illuminating the substrate during the deposition to improve long-term stability. Further processing steps to improve upon device stability will include H- dilution, and special dopants. In a preliminary sense, the PI's have explored these approaches with encouraging results. The use of a Ti dopant has increased photoconductivity, without increasing dark conductivity, to give an improved ratio. Illumination of the substrate with an intense light beam during MECR ( called PAMECR ) provides a material which has much improved stability, when later exposed to light, and greatly improved electrical properties. Use of photon assist has increased carrier lifetime ten-fold in a-Si and doubled crystal diameter in mc-Si. Use of this stabilized material should produce stabilized devices.PA-MECR with H-dilution and various dopants will be thoroughly studied to produce more stable a-Si and mc-Si for TFT's and PV devices. In-situ closed ion source mass spectroscopy (CIS-MS) will be used to correlate the composition of process gases with variations in process conditions. Films will be evaluated by a variety of techniques including FTIK, AFM, TEM, SIMS, AES, XPS, etc. Devices will be fabricated from the best materials and tested for long-term stability. The use of stabilized thin-film Si should lead to TFT's with reduced voltage-induced instability and PV devices with reduced photo-induced instability. Special buffer layers will be utilized on low-cost substrates to permit fabricating large-area devices at a reasonable cost. The SUNY beamline at Brookhaven National Lab will be used to explore the microscopic interfacial roughness between layers by grazing incidence X-ray scattering ( GIXS ) and the correlation with electrical performance. Thus, the primary goal will be developing improved mc-Si and aSi with an understanding of the role of the PA process using CIS-MS, FTIR, GIXS and other techniques to establish an optimum deposition procedure. The plasma chemistry will be correlated with bonding information in a-Si and H-passivation in mc-Si which relate to electrical properties, optical properties and stability.