Femtosecond Visible Pump Mid-IR Probe Study on the Effects of Surface Treatments on Ultrafast Photogenerated Carrier Dynamics in n-GaAs (100) Crystals

Abstract

The femtosecond visible pump mid-IR probe technique was employed to investigate photogenerated carrier dynamics in n-GaAs (100) crystals subjected to various surface treatments in a time domain of picoseconds–several tens of picoseconds. Pt- or Ru-treatment significantly accelerated the carrier recombination as a result of the introduction of surface states. The recombination rate was also increased by Au-treatment but less significantly than that by the Pt- or Ru-treatment. The effect of sulfide treatment on the recombination dynamics seemed to be rather small, although it has been reported that the density of surface states is decreased by the sulfide treatment.

Size-Dependent Carrier Dynamics in CdS Nanoparticles by Femtosecond Visible-Pump/IR-Probe Measurements

“…Time-Resolved Visible-Pump/IR-Probe Measurements. Observations of picosecond transitional absorption change were performed with a femtosecond time-resolved visible-pump/IR-probe system , as schematically shown in Figure . In all measurements, excitation wavelength was 395 nm (3.13 eV) and probe wavelength was tuned to avoid large absorption of H 2 O and D 2 O.…”

Effect of surface treatment with different sulfide solutions on the ultrafast dynamics of photogenerated carriers in GaAs(1 0 0)

“…In particular, it was found that after the treatment of GaAs(100) surface with aqueous sulfide solution the photoluminescence intensity increases, whereas the surface depletion layer width that characterizes the density of the occupied surface states remains unchanged [28]. The little effect of the treatment with aqueous sulfide solution on the surface recombination velocity in n-GaAs(100) was observed also in [20]. On the other hand, the treatment of the GaAs(100) surface with the solution of ammonium sulfide in 2-propanol resulted in considerable increase in photoluminescence intensity and in essential decrease of the surface depletion layer depth (i.e.…”

“…A femtosecond visible-pump infrared-probe system is described in detail elsewhere [20,21]. Briefly, a fs-pulse train generated by a Ti:sapphire regenerative amplifier system (Quantronics, 4812RGA/4823S/C) was used to pump two optical parametric …”