Characterization of GaAs heterolayers by micro-Raman spectroscopy

• Published in: Journal of crystal growth 1995-04, Vol.149 (3), p.167-174
• Main Authors: Ichimura, Masaya, Moriguchi, Yukihisa, Usami, Akira, Tabuchi, Masao, Sasaki, Akio
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Iii-v and ii-vi semiconductors; Infrared and raman spectra and scattering; Mechanical and acoustical properties; adhesion; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Physics; Solid surfaces and solid-solid interfaces; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties)
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/0022-0248(94)01023-4

GaAs heterolayers on (100) InAs and InP substrates were characterized by micro-Raman spectroscopy. The layers were 2μm thick and grown by molecular beam epitaxy at 480°C. A bevel was formed on each sample, and Raman scattering from the exposed interface region was collected. In close vicinity to the GaAs InAs interface, the frequency of the GaAs longitudinal-optical (LO) phonon was lower by about 3 cm −1 than at the as-grown surface. The LO shift decreased with increasing distance from the interface, but a small shift (about 0.5 cm −1) was still observed even at distances larger than 0.2 μm. The shift was believed to be due to residual misfit strain, and the value of biaxial strain was estimated to be about 0.6% at the interface. Almost the same results were obtained for GaAs InP , where the mismatch degree is smaller by a factor of two than in GaAs InAs . This would indicate that the residual strain in a thick heterolayer depends little on the initial misfit degree.