Morphological, luminescence and structural properties of nanocrystalline silicon thin films

Journal Article · Fri Mar 15 04:00:00 EDT 2013 · Materials Research Bulletin

DOI:https://doi.org/10.1016/J.MATERRESBULL.2012.11.102· OSTI ID:22290376

Kobayashi, Hikaru ^[1]; Inokuma, Takao ^[2]; Al-Hajry, Ali ^[3]

---

1. Institute of Scientific and Industrial Research, Osaka University (Japan)
2. Graduate School of Natural Science and Technology, Kanazawa University (Japan)
3. Physics Department, College of Science and Arts, Najran University (Saudi Arabia)

Highlights: ► The PL spectra showed two stronger peaks and one weaker peak. ► The PL peak energies and optical band-gap values were found higher than 1.12 eV. ► The structural change from an amorphous to nanocrystalline with increasing [SiH{sub 4}]. - Abstract: Nanocrystalline silicon (nc-Si) thin films deposited by plasma-enhanced chemical vapor deposition at various silane flow rates ([SiH{sub 4}]) are studied. The characterization of these films by high-resolution transmission electron microscopy, Raman spectroscopy and X-ray diffraction reveals that no film and very thin film is deposited at [SiH{sub 4}] = 0.0 and 0.1 sccm, respectively. In addition, the structural change from an amorphous to a nanocrystalline phase occurs at around [SiH{sub 4}] = 0.2 sccm. In this study, the importance of arriving species at surfaces and precursors is clearly demonstrated by the effect of a small addition of SiH{sub 4} on the frequency and width of a Raman peak and the structure of the grown film. The infrared spectroscopic analysis shows no hydrogen incorporation in the nc-Si film deposited at the low value of [SiH{sub 4}]. However, the intensity of the peak around 2100 cm{sup −1} due to SiH decreases with increasing [SiH{sub 4}]. All fabricated films give photoluminescence in the range between 1.7 and 2.4 eV at room temperature, indicating enlargement of the band-gap energy. The presence of very small crystallites leads to the appearance of quantum confinement effects. The variations of the photoluminescence energy and spectral width are well correlated with the structural properties of the films such as crystallite size, crystalline volume fraction, and the density of Si-H bonds.

• OSTI ID: 22290376
• Journal Information: Materials Research Bulletin, Journal Name: Materials Research Bulletin Journal Issue: 3 Vol. 48; ISSN MRBUAC; ISSN 0025-5408
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CHEMICAL VAPOR DEPOSITION
CRYSTAL STRUCTURE
CRYSTALS
NANOSTRUCTURES
OPTICAL PROPERTIES
PHOTOLUMINESCENCE
RAMAN SPECTROSCOPY
SILANES
SILICON
THIN FILMS