Photoreflectance and X-ray studies of silicon films on sapphire

• Published in: Materials letters 1989-04, Vol.8 (1), p.64-68
• Main Authors: Giordana, Adriana, Glosser, R., Pellegrino, Joseph G., Qadri, Syed, Richmond, Eliezer Dovid
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Physics
• ISSN: 0167-577X; 1873-4979
• DOI: 10.1016/0167-577X(89)90099-2

Photoreflectance was used for the first time to study silicon films on sapphire (SOS). The film thicknesses ranged from 150 to 40 000 Å. The 3.4 eV structure was monitored with bulk silicon as a standard. A shift of this structure toward lower energies was observed for the thinner films. As the film thickness increased from 1000 to 40000 Å, the energy shift appeared to oscillate about the energy value associated with the bulk silicon sample. The energy shift with thickness of the photoreflectance structure is consistent with that calculated from the X-ray measured strain for the thicker films. The short optical penetration depth at 3.4 eV (≈ 100 Å) is essential to allowing photoreflectance investigation of films of this order of thickness.