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

9902437安德森非晶硅（a-Si）和微晶硅（mc-Si）是用于平板显示器中的薄膜晶体管（TFT）和用于光致发光（PV）的技术上重要的材料。这两种材料在暴露于光或施加电压时都易于降解。 这种不稳定性导致非最佳器件性能，即使已知存在部分稳定材料的方法。 本研究将通过引入特殊的加工技术来改善这些不稳定性。 改进的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）被证明可以产生更稳定的材料，将用于沉积，并在沉积过程中通过照射衬底来辅助以提高长期稳定性。 提高器件稳定性的进一步处理步骤将包括H-稀释和特殊掺杂剂。 在初步意义上，PI已经探索了这些方法，并取得了令人鼓舞的结果。 Ti掺杂剂的使用具有增加的光电导性，而不增加暗电导率，以得到改善的比率。 在MECR（称为PAMEC R）期间用强光束照射衬底提供了一种材料，该材料在随后暴露于光时具有大大改善的稳定性和大大改善的电性能。 光子辅助的使用使a-Si中的载流子寿命增加了十倍，使mc-Si中的晶体直径增加了一倍。 使用这种稳定的材料应生产稳定的设备。将彻底研究具有H稀释和各种掺杂剂的PA-MECR，以生产用于TFT和PV设备的更稳定的a-Si和mc-Si。 原位封闭离子源质谱（CIS-MS）将用于将工艺气体的成分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，西姆斯，AES，XPS等。设备将由最好的材料制成，并进行长期稳定性测试。 使用稳定的薄膜Si应导致具有降低的电压诱导的不稳定性的TFT和具有降低的光诱导的不稳定性的PV器件。 特殊的缓冲层将用于低成本的基板上，以允许以合理的成本制造大面积的设备。 布鲁克海文国家实验室的SUNY光束线将用于通过掠入射X射线散射（GIXS）探索层间的微观界面粗糙度以及与电气性能的相关性。 因此，主要目标将是开发改进的mc-Si和aSi，了解PA工艺的作用，使用CIS-MS，FTIR，GIXS和其他技术来建立最佳沉积程序。 等离子体化学将与a-Si中的键合信息和mc-Si中的H钝化相关，这些信息与电学性质、光学性质和稳定性相关。

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.