Picosecond and subpicosecond optical properties of GaAs/Al[sub x]Ga[sub 1[minus]x]As quantum wells and superlattices

Miscellaneous · Fri Jan 01 00:00:00 EST 1993

OSTI ID:7302836

Bouchalkha, A

The optical properties of GaAs/Al[sub x]Ga[sub 1[minus]x]As quantum wells (QW's) and ZnSe epilayer were investigated in the picosecond and subpicosecond time scales. The phonon confinement and propagation were investigated systematically using time-resolved Raman scattering techniques on several series of GaAs/Al[sub x]Ga[sub 1[minus]x]As samples. The ultrafast carrier and exciton dynamics were investigated by degenerate four-wave mixing (DFWM) techniques with subpicosecond time resolution. The authors have observed a confined-to-propagating GaAs LO phonon transition in GaAs/Al[sub x]Ga[sub 1[minus]x]As QW's as the barrier width (L[sub b]) decreased for three series of samples with x = 1, x = 0.4, and x = 0.3. The results on the x < 0.3 series showed practically no LO phonon confinement regardless of the barrier width considered. This result implies that the electron-LO phonon scattering rates in these heterostructures are essentially the same as that of bulk GaAs for x < 0.3. The authors have also reported the first estimates of the GaAs LO phonon penetration depth ([lambda]) and observed a sharp increase in [lambda] as x decreased. Simple theoretical estimates of [lambda] were found in excellent agreement with the experimental values. The DFWM experiments were performed as a function of temperature, excitation energy, and power on a GaAs/Al[sub 0.3]Ga[sub 0.7]As superlattice (SL) and a ZnSe epilayer. The authors have observed strong quantum beats between the heavy-hole (HH) and light-hole (LH) excitons in the SL sample. The authors have also observed the appearance of long time constant at energy detunings below the HH resonance. The power dependent study has led us to observe interesting saturation effects. In the ZnSe sample the authors obtained the very first subpicosecond DFWM results. Some of these results are in contrast with those of GaAs/Al[sub x]Ga[sub 1[minus]x]As QW's.

• Research Organization: Oklahoma State Univ., Stillwater, OK (United States)
• OSTI ID: 7302836
• Resource Relation: Other Information: Thesis (Ph.D.)
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALUMINIUM ARSENIDES
OPTICAL PROPERTIES
GALLIUM ARSENIDES
ZINC SELENIDES
CARRIER MOBILITY
ELECTRON-PHONON COUPLING
FREQUENCY MIXING
QUANTUM ELECTRONICS
RAMAN SPECTRA
SEMICONDUCTOR MATERIALS
SUPERLATTICES
ALUMINIUM COMPOUNDS
ARSENIC COMPOUNDS
ARSENIDES
CHALCOGENIDES
COUPLING
GALLIUM COMPOUNDS
MATERIALS
MOBILITY
PHYSICAL PROPERTIES
PNICTIDES
SELENIDES
SELENIUM COMPOUNDS
SPECTRA
ZINC COMPOUNDS
360606* - Other Materials- Physical Properties- (1992-)
665400 - Quantum Physics Aspects of Condensed Matter- (1992-)