Modulated reflectivity probing of quantum dot and wetting layer states in InAs/GaInAsP/InP quantum dot laser structures

✍ Scribed by Sęk, G. ;Motyka, M. ;Kudrawiec, R. ;Misiewicz, J. ;Lelarge, F. ;Rousseau, B. ;Patriarche, G.

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 303 KB
• Volume: 204
• Category: Article
• ISSN: 0031-8965
• DOI: 10.1002/pssa.200673325

✦ Synopsis

Abstract

InAs/GaInAsP quantum dot (QD) structure grown by gas source molecular beam epitaxy on InP (100) substrate and designed as an active region for laser applications at 1.55 μm wavelength range has been investigated by optical spectroscopy in order to probe its energy electronic structure. The advantages of the modulated reflectivity measurements (in a form of photoreflectance – PR) have been used to detect the optical transitions related to all relevant parts of the structure like cladding material, quaternary barriers, wetting layer and finally quantum dots. Our theoretical analysis based on effective mass approximation calculations has shown that two high energy PR features above the QD ground state emission are related to heavy hole and light hole ground state transitions in the InAs wetting layer which is 3–4 monolayers thick. Moreover, the confinement potential for the dots is shallow enough to confine one electron state only and hence a single QD heavy hole transition has been observed in PR. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)