By a News Reporter-Staff News Editor at Energy Weekly News -- Current study results on Solar Energy have been published. According to news originating from Trondheim, Norway, by VerticalNews correspondents, research stated, "Surface passivation by hydrogenated amorphous silicon nitride (a-SiNx:H) is determined by the combined effect of two mechanisms: so-called chemical passivation by reducing the density of interface states (D-it) and field-effect passivation as a result of the number of fixed charges (Q(f)) at the interface with Si. These are related to the K defect center: *Si-N-3."
Our news journalists obtained a quote from the research from Foundation for Scientific and Industrial Research, "Defects near the interface (in both Si as in a-SiNx:H), modeled by force field Molecular Dynamics (MD) and ab initio Density Functional Theory (DFT), can be related to Q(f) and D-it measured experimentally using CV-MIS (Capacitance-Voltage Metal-Insulator-Semiconductor). The compositional build up at the interface as is determined by HRTEM (High Resolution Transmission Electron Microscopy) and modeled by MD corresponds to each other; a gradual change from Si to the bulk a-SiNx:H composition in the first 2 nm of the a-SiNx:H layer. At the c-Si side a highly distorted layer (about 1-3 nm) caused by the insertion of N and/or H is found. The insertion and adhesion of N into and at the Si surface is called nitridation and can be altered by using a NH3 plasma prior to a-SiNx:H deposition. HRTEM image analysis shows that by varying the nitridation of the Si surface the amount and penetration depth of N inside the Si surface is altered. Using MD modeling, it is shown that this process changes the amount of K-centers at the surface, which explains the variation in Q(f) and D-it that is found experimentally. Ab initio DFT studies of a-SiNx:H (x=1.17) show that K-centers and Si atoms in distorted configuration, are the dominating defects resulting in a higher D-it."
According to the news editors, the research concluded: "For lower x (x=1) the D-it caused by K-centers increases, which is observed experimentally too."
For more information on this research see: The interface of a-SiNx:H and Si: Linking the nano-scale structure to passivation quality. Solar Energy Materials and Solar Cells, 2014;120():311-316. Solar Energy Materials and Solar Cells can be contacted at: Elsevier Science Bv, PO Box 211, 1000 Ae Amsterdam, Netherlands. (Elsevier - www.elsevier.com; Solar Energy Materials and Solar Cells - www.elsevier.com/wps/product/cws_home/505675)
The news correspondents report that additional information may be obtained from M. Lamers, SINTEF, Mat & Chem, NO-7465 Trondheim, Norway. Additional authors for this research include L.E. Hintzsche, K.T. Butler, P.E. Vullum, C.M. Fang, M. Marsman, G. Jordan, J.H. Harding, G. Kresse and A. Weeber.
Keywords for this news article include: Norway, Europe, Trondheim, Solar Energy
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