Das Debajyoti, Raha Debnath, Bhattacharya Koyel
Nano-Science Group, Energy Research Unit, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India.
J Nanosci Nanotechnol. 2009 Sep;9(9):5614-21. doi: 10.1166/jnn.2009.1151.
The evolution of nc-Si network and the control of its growth within quantum dot structures have been systematically studied by He/H2 plasma assistance in SiH4. Using the beneficial aspects of He* and He+ in the purely helium-diluted silane plasma and optimizing the process parameters, nanocrystalline silicon films are produced at high growth rates. The nc-Si:H network of increasing electrical conductivity and improved crystallinity are obtained with simultaneously increasing deposition rates, which deserve extensive technological impact. Starting with a mixed phase heterogeneous matrix in the neighborhood of amorphous-to-crystalline transition zone, the effect of H2 in the reconstruction of the network, triggering nanocrystallization, was studied using (SiH4+He+H2)-plasma. A radical change in the materials properties has been accomplished by the inclusion of a small amount of H2 as the component diluent. Sharp rise in the overall crystallinity, well aligned crystallographic lattice distribution, gross removal of porosity and sharp elevation of electrical conductivity by several orders of magnitude are the consequences which are accompanied by a relatively insignificant lowering in the growth rate because of required H2-dilution in trivial amounts. Partial hydrogenation to the mostly He diluted SiH4 plasma has been identified as the favored route for attaining spontaneous nanocrystallization in the Si-network and its confinement of structures within quantum dot dimensions.
通过在硅烷中采用氦/氢气等离子体辅助，系统研究了纳米晶硅网络的演化及其在量子点结构中的生长控制。利用纯氦稀释硅烷等离子体中氦原子和氦离子的有益作用并优化工艺参数，可实现纳米晶硅薄膜的高速生长。随着沉积速率的提高，可获得电导率增加且结晶度提高的氢化纳米晶硅网络，这具有广泛的技术影响。从非晶态到晶态转变区附近的混合相非均质基体开始，利用（硅烷+氦+氢气）等离子体研究了氢气在网络重构、引发纳米晶化中的作用。通过加入少量氢气作为组分稀释剂，材料性能发生了根本性变化。整体结晶度急剧提高、结晶晶格分布良好对齐、孔隙率大幅降低以及电导率急剧提高几个数量级，这些结果伴随着因所需少量氢气稀释而导致的生长速率相对较小的降低。已确定对主要由氦稀释的硅烷等离子体进行部分氢化是在硅网络中实现自发纳米晶化及其在量子点尺寸内限制结构的有利途径。
