Initial Nucleation Approach for Large Grain-Size and High-Quality Microcrystalline Silicon Active Layer in Thin Film Transistors

摘要

High mobility and stability are critical factors for thin film transistor (TFT) device quality. These parameters are directly dependent on the crystalline structure of the active layer materials. In this paper, the early nucleation approach was performed for increasing the crystalline grain size of microcrystalline silicon (mu c-Si:H) active layer for TFT device quality. The crystalline nucleation is delicately regulated in an intense hydrogen plasma environment using the plasma enhanced chemical vapor deposition (PECVD). When compared to mu c-Si:H deposition without the nucleation approach, the crystalline volume factor of mu c-Si:H increased from 60 to over 80 by using the nucleation technique. The nucleation increases the crystalline grain size by five orders of magnitude. Furthermore, the surface roughness of mu c-Si:H is decreased from 13.7 nm to 7.1 nm. A forming-gas post-annealing treatment (<= 400 degrees C) is used to minimize defect density. With a low microstructural factor, thermal-treated film quality improves dramatically. Nucleation approach is to be a simple and efficient for producing high-quality TFT devices.