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CdTe surface roughness by Raman spectroscopy using the 830 nm wavelength
C Frausto-Reyes1, J Rafael Molina-Contreras, C Medina-Gutiérrez
1Centro de Investigaciones en Optica A.C., Unidad Aguascalientes, Prolong., Constitución 607, Fracc. Reserva Loma Bonita, C.P. 20200, Apartado Postal 507, Ags., México. cfraus@cio.mx
Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
|December 6, 2005
Summary
Raman spectroscopy with 830 nm excitation can monitor cadmium telluride (CdTe) surface roughness. This method shows a direct link between spectral features and roughness, unlike other wavelengths tested.
Area of Science:
- Materials Science
- Spectroscopy
- Surface Science
Background:
- Surface roughness is a critical parameter in semiconductor wafer quality.
- Accurate measurement of surface roughness is essential for optimizing growth processes.
Purpose of the Study:
- To investigate the potential of Raman spectroscopy for detecting surface roughness of cadmium telluride (CdTe) wafers.
- To establish a correlation between Raman spectral features and surface roughness.
Main Methods:
- Raman spectroscopy was employed using three excitation wavelengths: 514.5, 632.8, and 830.0 nm.
- Atomic force microscopy (AFM) was used to measure the actual surface roughness in specific sample zones.
Main Results:
- A direct correspondence between Raman spectral structure and surface roughness was observed only with the 830 nm excitation wavelength.
- No clear correlation was found between spectral structure and surface roughness for the 514.5 nm and 632.8 nm wavelengths.
Conclusions:
- Raman spectroscopy, particularly at 830 nm, shows promise as an effective on-line tool for monitoring CdTe surface roughness during growth.
- The choice of excitation wavelength is crucial for utilizing Raman spectroscopy as a surface roughness diagnostic tool.