Ultrafast Dynamics of Excitons in GaAs Single Quantum Wells
Phase and orientational relaxation of excitons in a 12nm GaAs single quantum well are measured by time-resolved degenerate four-wave-mixing. Dephasing studies of excitons subjected to collisions with acoustic phonons, free carriers or incoherent excitons are applied to analyze the respective interaction mechanisms. Comparison of the results with data for 3D excitons in bulk GaAs reveal a distinct dependence of the relaxation dynamics as well as the interaction of excitons with other quasi-particles on the dimensionality of the system. Finally we show that the exciton lifetime increases with decreasing dephasing time because the oscillator strength of the excitonic transition varies with the size of the coherence volume of the exciton wavefunction.
KeywordsFree Carrier Quantum Well Acoustic Phonon Radiative Lifetime Single Quantum Well
Unable to display preview. Download preview PDF.
- 1.D. S. Chemla, S. Schmitt-Rink, and D. A. B. Miller, “Nonlinear Optical Properties of Semiconductor Quantum Wells”, in: “Nonlinear Optical Properties of Semiconductors”, H. Haug, ed. Academic New York, (1988) and D. S. Chemla, D. A. B. Miller, P. W. Smith, A. C. Gossard and W. Wiegmann, “Room Temperature Excitonic Nonlinear Absorption and Refraction in GaAs/AlGaAs Multiple Quantum Well Structures”, IEEE J. Quant. Electr. QE-20, 265 (1984).Google Scholar
- 6.L. Schultheis, J. Kühl, A. Honold and C.W. Tu, “Ultrafast Relaxation of Nonthermal Wannier Excitons in GaAs”, in: Ultrafast Phenomena V, Springer Series in Chemical Physics 46, Eds. G. R. Fleming and A. E. Siegman (Springer, Berlin 1986), p. 201.Google Scholar
- 7.L. Schultheis, J. Kühl, A. Honold and C. W. Tu, “Ultrafast Relaxation of Nonthermal Excitons in GaAs” in: Proceedings of 18th Int. Conf. on the Physics of Semiconductors, Ed. O. Engström (World Scientific, Singapore 1987), p. 1397.Google Scholar
- 8.L. Schultheis, J. Kühl, A. Honold and C. W. Tu, “Optical Dephasing of Wannier Excitons in GaAs” in: Excitons in Confined Systems, Eds. R. Del Sole, A. D. Andrea and A. Lapiccirella (Springer, Berlin, 1988).Google Scholar
- 9.H. J. Eichler, P. Guenter and D. W. Pohl, “Laser-Induced Dynamic Gratings”, Springer Series in Opt. Sciences, Springer Verlag, Berlin, Heidelberg, New York (1986).Google Scholar
- 10.B. S. Wherrett, A. L. Smirl and T. F. Bogess, “Theory of Degenerate Four-Wave-Mixing in Picosecond Excitation-Probe Experiments”, IEEE J. Quant. Electr. QE-19, 680 (1983), and A. L. Smirl, T. F. Bogess, B. S. Wherrett, G. P. Perryman and A. Miller, “Picosecond Transient Orientational and Concentration ratings in Germanium”, IEEE J. Quant. Electr. QE-19, 690 (1983).ADSCrossRefGoogle Scholar
- 17.An improved analysis of the diffraction curves taking into account the inhomogeneous line broadening is presently under study. The absolute values for T2 may increase by about 20-30% after this correction, but the general statements of this paper will remain unaffected.Google Scholar