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Updated: May 17, 2026
High Speed Sub-GHz Spectrometer for Brillouin Scattering Analysis
Published on: December 22, 2015
A rapid reflectance-difference spectrometer for real-time semiconductor growth monitoring with sub-second time
O Núñez-Olvera1, R E Balderas-Navarro, J Ortega-Gallegos
1Instituto de Investigación en Comunicación Óptica, Universidad Autónoma de San Luis Potosí, San Luis Potosí, San Luis Potosí 78216, Mexico.
Abstract:
We report on a rapid, 32-channel reflectance-difference (RD) spectrometer with sub-second spectra acquisition times and ΔR/R sensitivity in the upper 10(-4) range. The spectrometer is based on a 50 kHz photo-elastic modulator for light polarization modulation and on a lock-in amplifier for signal harmonic analysis. Multichannel operation is allowed by multiplexing the 32 outputs of the spectrometer into the input of the lock-in amplifier. The spectrometer spans a wavelength range of 230 nm that can be tuned to cover E(1) and E(1) + Δ(1) transitions for a number of III-V semiconductors at epitaxial growth temperatures, including GaAs, InAs, AlAs, and their alloys. We present two examples of real-time measurements to demonstrate the performance of the RD spectrometer, namely, the evolution of the RD spectrum of GaAs (001) annealed at 500 °C and the time-dependent RD spectrum during the first stages of the epitaxial growth of In(0.3)Ga(0.7)As on GaAs (001) substrates.
