A study of the low-energy interference oscillations in photoreflectance of GaAsSb/GaAs quantum well structures

✍ Scribed by Blume, G. ;Hosea, T. J. C. ;Sweeney, S. J.

• Book ID: 105363103
• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 483 KB
• Volume: 202
• Category: Article
• ISSN: 0031-8965
• DOI: 10.1002/pssa.200460904

✦ Synopsis

Abstract

We present a room temperature photoreflectance (PR) investigation of GaAsSb/GaAs/AlGaAs quantum well (QW) structures grown on GaAs substrates by molecular beam epitaxy. We encounter strong low energy interference oscillations (LEIO), which tend to obscure any PR signals arising from the QW. By varying the angle of incidence, we exploit the LEIO to estimate the refractive index of the layer responsible and thus identify it. Furthermore, we demonstrate the ability to model the lineshapes of the observed LEIO accurately, through calculations of the Seraphin coefficients. This then allows us to deduce the actual thickness of the layer responsible, which is found to be close to the nominal value. These calculations in turn suggest a way to avoid the LEIO – by shortening the laser excitation wavelength. This successfully reveals good PR signals from the QW region, yielding several transition wavelengths, which we then compare with a theoretical model, assuming a small type II offset between GaAsSb QW and GaAs spacer layers. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)