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Ultrafast Dynamics of Photoexcited Charge Carriers in In{sub 0.53}Ga{sub 0.47}As/In{sub 0.52}Al{sub 0.48}As Superlattices under Femtosecond Laser Excitation

Journal Article · · Semiconductors
; ; ;  [1]; ; ; ;  [2]
  1. Russian Academy of Sciences, Institute of Ultrahigh-Frequency Semiconductor Electronics (Russian Federation)
  2. Moscow Technological University (MIREA) (Russian Federation)
The results of experimental studies of the time dynamics of photoexcited charge carriers in In{sub 0.53}Ga{sub 0.47}As/In{sub 0.52}Al{sub 0.48}As superlattices grown by molecular-beam epitaxy on a GaAs substrate with a metamorphic buffer are reported. On the basis of the results of the numerical simulation of band diagrams, the optimal thickness of the In{sub 0.52}Al{sub 0.48}As barrier layer (4 nm) is chosen. At this thickness, the electron wave functions in In{sub 0.53}Ga{sub 0.47}As substantially overlap the In{sub 0.52}Al{sub 0.48}As barriers. This makes it possible to attain a short lifetime of photoexcited charge carriers (τ ~ 3.4 ps) at the wavelength λ = 800 nm and the pumping power 50 mW without doping of the In{sub 0.53}Ga{sub 0.47}As layer with beryllium. It is shown that an increase in the wavelength to λ = 930 nm (at the same pumping power) yields a decrease in the lifetime of photoexcited charge carriers to τ ~ 2 ps. This effect is attributed to an increase in the capture cross section of trapping states for electrons with lower energies and to a decrease in the occupancy of traps at lower excitation densities.
OSTI ID:
22749886
Journal Information:
Semiconductors, Journal Name: Semiconductors Journal Issue: 7 Vol. 52; ISSN SMICES; ISSN 1063-7826
Country of Publication:
United States
Language:
English