Study of surface roughness using spectral reflectance measurements recorded during the MOVPE of InAs/GaAs heterostructures

• Published in: Physica. E, Low-dimensional systems & nanostructures Vol. 44; no. 7-8; pp. 1282 - 1287
• Main Authors: Massoudi, I., Habchi, M.M., Rebey, A., El Jani, B.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-04-2012; Elsevier
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Fullerenes and related materials; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Physics; Visible and ultraviolet spectra; Atomic force microscopy; Gallium arsenides; Spectroscopic ellipsometry; Atmospheric pressure; Roughness; VPE; Layer thickness; Indium arsenides; III-V compound; Reflectivity; Reflection spectrum; MOVPE method; Size effect; Growth mechanism; Transfer matrix method; Crystal faces; Effective medium model; Heterostructures; III-V semiconductors
• ISSN: 1386-9477; 1873-1759
• DOI: 10.1016/j.physe.2012.02.002

InAs layers were elaborated on semi-insulating GaAs (100) substrates in a horizontal atmospheric pressure MOVPE reactor at a temperature of 450°C. The growth process was in situ monitored by spectral reflectance (SR) in the wavelength range 200–1100nm. The best fittings of the experimental responses using the transfer matrix method (TMM) combined with the Bruggeman effective medium approximation (EMA), permit the study of the surface roughness during the growth and the determination of the InAs layer thickness at different phases of the epitaxy. The calculations were in good agreement with the ex situ spectroscopic ellipsometry (SE) measurements. The roughness modeled by an effective layer thickness, obtained indirectly from SR and SE measurements, was well correlated with direct measurements using the atomic force microscopy (AFM). Simulated roughness closely obeys a relationship of the form of deff(SR/SE)≈1.5RMS (AFM) where RMS (AFM) is the root-mean-square roughness measured by AFM.
► We present a study of the InAs surface roughness grown on GaAs substrate by MOVPE. ► We use in situ spectral reflectance to quantify the uniformity of the roughness. ► Other ex situ techniques of characterization were used to compare the obtained results.