Surface roughness estimation of MBE grown CdTe/GaAs(211)B by ex-situ spectroscopic ellipsometry

Journal Article · Fri Jul 15 04:00:00 EDT 2016 · AIP Advances

DOI:https://doi.org/10.1063/1.4959223· OSTI ID:22611462

Karakaya, Merve ^[1]; Bilgilisoy, Elif; Arı, Ozan; Selamet, Yusuf ^[2]

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1. Department of Material Science and Engineering, Izmir Institute of Technology, Izmir 35430 (Turkey)
2. Department of Physics, Izmir Institute of Technology, Izmir 35430 (Turkey)

Spectroscopic ellipsometry (SE) ranging from 1.24 eV to 5.05 eV is used to obtain the film thickness and optical properties of high index (211) CdTe films. A three-layer optical model (oxide/CdTe/GaAs) was chosen for the ex-situ ellipsometric data analysis. Surface roughness cannot be determined by the optical model if oxide is included. We show that roughness can be accurately estimated, without any optical model, by utilizing the correlation between SE data (namely the imaginary part of the dielectric function, <ε{sub 2} > or phase angle, ψ) and atomic force microscopy (AFM) roughness. <ε{sub 2} > and ψ values at 3.31 eV, which corresponds to E{sub 1} critical transition energy of CdTe band structure, are chosen for the correlation since E{sub 1} gives higher resolution than the other critical transition energies. On the other hand, due to the anisotropic characteristic of (211) oriented CdTe surfaces, SE data (<ε{sub 2} > and ψ) shows varieties for different azimuthal angle measurements. For this reason, in order to estimate the surface roughness by considering these correlations, it is shown that SE measurements need to be taken at the same surface azimuthal angle. Estimating surface roughness in this manner is an accurate way to eliminate cumbersome surface roughness measurement by AFM.

• OSTI ID: 22611462
• Journal Information: AIP Advances, Journal Name: AIP Advances Journal Issue: 7 Vol. 6; ISSN AAIDBI; ISSN 2158-3226
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANISOTROPY
ATOMIC FORCE MICROSCOPY
CADMIUM TELLURIDES
CORRELATIONS
DATA ANALYSIS
DIELECTRIC MATERIALS
ELLIPSOMETRY
FILMS
GALLIUM ARSENIDES
LAYERS
MOLECULAR BEAM EPITAXY
OPTICAL MODELS
OPTICAL PROPERTIES
OXIDES
RESOLUTION
ROUGHNESS
SURFACES
THICKNESS