Lamers, M., Hintzsche, L.E., Butler, K.T. et al. (7 more authors) (2014) The interface of a-SiNx:H and Si: Linking the nano-scale structure to passivation quality. Solar Energy Materials and Solar Cells, 120 (Part A). pp. 311-316. ISSN 0927-0248
Abstract
Surface passivation by hydrogenated amorphous silicon nitride (a-SiN x:H) is determined by the combined effect of two mechanisms: so-called chemical passivation by reducing the density of interface states (Dit) and field-effect passivation as a result of the number of fixed charges (Qf) at the interface with Si. These are related to the K defect center: *Si-N3. 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 Qf and Dit 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 Qf and Dit that is found experimentally. Ab initio DFT studies of a-SiN x:H (x=1.17) show that K-centers and Si atoms in distorted configuration, are the dominating defects resulting in a higher Dit. For lower x (x=1) the Dit caused by K-centers increases, which is observed experimentally too. © 2013 Elsevier B.V.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2013 Elsevier. This is an author produced version of a paper subsequently published in Solar Energy Materials and Solar Cells. Uploaded in accordance with the publisher's self-archiving policy. Article available under the terms of the CC-BY-NC-ND licence (https://creativecommons.org/licenses/by-nc-nd/4.0/) |
Keywords: | Silicon nitride; Passivation; Interface; Nitridation; Fixed charge |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Engineering (Sheffield) > Department of Materials Science and Engineering (Sheffield) |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 08 Apr 2016 13:44 |
Last Modified: | 10 Apr 2016 06:24 |
Published Version: | https://dx.doi.org/10.1016/j.solmat.2013.04.026 |
Status: | Published |
Publisher: | Elsevier |
Refereed: | Yes |
Identification Number: | 10.1016/j.solmat.2013.04.026 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:97831 |