Effect of Hydrogen Dilution Profiling on the Microscopic Structure of Amorphous and Nanocrystalline Silicon Mixed-Phase Solar Cells

Baojie Yan, Chun Sheng Jiang, Fa Yan, Laura Sivec, Jeffrey Yang, Subhendu Guha, M. M. Al-Jassim

Research output: Contribution to journalArticlepeer-review

4 Scopus Citations


Microscopic structure and solar cell performance in hydrogenated mixed-phase thin film silicon (Si:H) solar cells are studied. The samples were made with RF glow discharge with different hydrogen dilution profiles. The material properties were measured with Raman, X-TEM, AFM, and C-AFM. Several interesting phenomena are observed. First, the cone-structured nanocrystalline aggregations were formed when a constant hydrogen dilution was used. Second, no uniform block-like (or cylinder-like) structured nanocrystalline clusters were observed even when hydrogen dilution profiling was optimized for this purpose. Instead, tree-like structured nanocrystalline clusters were formed and embedded in the intrinsic layer. Third, the magnitude of light-induced Voc increase was reduced by hydrogen dilution profiling. When the dilution profiling was sufficiently steep, no light-induced Voc increase was observed. Instead, the Voc decreased after light-soaking regardless of the crystalline volume fraction. In addition, AFM and C-AFM showed that this type of mixed-phase material has hill-like surface structure, where the hills correspond to nanocrystalline clusters. The local current density in hill-like areas was much higher in the samples made with constant hydrogen dilution than those using hydrogen dilution profiling. For the samples with a very steep hydrogen dilution profiling, the local forward current density is very low. Based on our previous model, the light-induced Voc increase depends on the formation of the current path in the nanocrystalline cluster areas. When a steep hydrogen dilution profiling is used, the tree-like nanocrystalline clusters are isolated and embedded in the intrinsic layer, therefore, no high current paths are formed and no light-induced Voc increase is observed.

Original languageAmerican English
Pages (from-to)513-516
Number of pages4
JournalPhysica Status Solidi (C) Current Topics in Solid State Physics
Issue number3-4
StatePublished - 2010
Event23rd International Conference on Amorphous and Nanocrystalline Semiconductors, ICANS23 - Utrecht, Netherlands
Duration: 23 Aug 200928 Aug 2009

NREL Publication Number

  • NREL/JA-520-48845


  • thin film solar cells


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