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。当受到光照或施加电压时，这两种材料都容易降解。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处理技术来改善这些不稳定性。改进的a-Si和mc-Si将用于制造TFT和PV器件。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，在沉积过程中通过照亮衬底来帮助提高长期稳定性。进一步的处理步骤，以提高设备的稳定性将包括氢稀释，和特殊的掺杂剂。从初步意义上说，PI已经探索了这些方法，并取得了令人鼓舞的结果。钛掺杂剂的使用增加了光电导率，而不增加暗电导率，从而提高了比率。在MECR（称为PAMECR）过程中，用强光束照射基板提供了一种材料，当稍后暴露在光线下时，这种材料的稳定性大大提高，并且大大提高了电性能。光子辅助的使用使a-Si的载流子寿命增加十倍，mc-Si的晶体直径增加一倍。使用这种稳定的材料应该产生稳定的装置。将深入研究h稀释和各种掺杂剂的PA-MECR，以生产更稳定的用于TFT和PV器件的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组成与工艺条件的变化联系起来。薄膜将通过各种技术进行评估，包括FTIK， AFM， TEM， SIMS， AES， XPS等。设备将由最好的材料制造，并进行长期稳定性测试。稳定硅薄膜的使用将导致TFT具有降低的电压诱导不稳定性和PV器件具有降低的光诱导不稳定性。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器件。布鲁克海文国家实验室的纽约州立大学光束线将用于通过掠入射x射线散射（GIXS）探索层间微观界面粗糙度及其与电性能的相关性。因此，主要目标将是开发改进的mc-Si和aSi，同时了解PA过程的作用，使用CIS-MS， FTIR， GIXS和其他技术来建立最佳沉积过程。等离子体化学将与a-Si的成键信息和mc-Si的h钝化相关，这关系到电学性质、光学性质和稳定性。

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.