Determination of the intervalley X 6 --> Gamma 6 , L 6 scattering time and the density of states effective mass of the X 7 band in GaAs by picosecond time-resolved absorption spectroscopy

Abstract

The dynamics of electrons in the X 6 valley for a GaAs crystal was measured by time-resolved absorption spectroscopy. An infrared picosecond probe pulse was used to monitor the growth and decay of the population in the X o valley subsequent to excitation by a 527 nm pump pulse. The intervalley X , F 6' L 6 scattering time was determined from the time evolution of electrons in the x 6 valley to be 700 500 fs by a rate equation analysis. The X 6-X absorption spectrum of GaAs was obtained by the time-resolved pump-JR-probe technique by varying the probe wavelength from 2.16 m to 3.9 m. It gives the energy gap between the minima of the X and X bands to be 0.345 eV, and the density of states effective mass for the X band to be 0.48 m