A study of crystallinity in amorphous Si thin films for silicon heterojunction solar cells

Kwang Sun Ji, Junghoon Choi, Hyunjin Yang, Heon Min Lee, Donghwan Kim

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)

Abstract

In this work we analyzed the crystallinity of hydrogenated amorphous Si thin films deposited on n-type Si substrates using the effective medium approximation (EMA) method of a spectroscopic ellipsometer (SE) and evaluated their passivation quality by measuring effective carrier lifetime (τeff) and implied Voc using quasi-steady-state photo conductance decay (QSSPC) simultaneously. The crystalline volume fraction of doped a-Si:H layers using RF-PECVD was controlled from ∼0% (nearly full amorphous phase) to above 90% (nearly polycrystalline phase) through varying deposition conditions. The passivation property depended on the crystallinity more strongly for p-a-Si:H than n-a-Si:H of which crystallinity was more sensitive to deposition rate relatively. The implied Voc above 650 mV was achieved with crystallinity less than about 5% for p-a-Si:H and 20% for n-a-Si:H. The HRTEM images confirmed the reliability of SE analysis with EMA modeling and showed the maximum part of crystalline phase exists at the interface of a-Si:H and c-Si in the form of epitaxial growth configuration. By the optimization of each a-Si:H deposition conditions 17.17% the cell efficiency was accomplished on non-textured substrate.

Original languageEnglish
Pages (from-to)203-206
Number of pages4
JournalSolar Energy Materials and Solar Cells
Volume95
Issue number1
DOIs
Publication statusPublished - 2011 Jan

Keywords

  • Crystallinity
  • Ellipsometric analysis
  • Hetero-interface

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Renewable Energy, Sustainability and the Environment
  • Surfaces, Coatings and Films

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