title: A rapid reflectance-difference spectrometer for real-time semiconductor growth monitoring with sub-second time resolution.
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.
authors.affiliation: Instituto de Investigación en Comunicación Óptica, Universidad Autónoma de San Luis Potosí, San Luis Potosí, San Luis Potosí 78216, Mexico.
authors.forename: O
authors.initials: O
authors.lastname: Núñez-Olvera
authors.forename: R E
authors.initials: RE
authors.lastname: Balderas-Navarro
authors.forename: J
authors.initials: J
authors.lastname: Ortega-Gallegos
authors.forename: L E
authors.initials: LE
authors.lastname: Guevara-Macías
authors.forename: A
authors.initials: A
authors.lastname: Armenta-Franco
authors.forename: M A
authors.initials: MA
authors.lastname: Lastras-Montaño
authors.forename: L F
authors.initials: LF
authors.lastname: Lastras-Martínez
authors.forename: A
authors.initials: A
authors.lastname: Lastras-Martínez