Time-resolved DFWM, excite/probe and transient grating studies of In<sub>x</sub>Ga<sub>1-x</sub>As/GaAs superlattices
G V M Williams; C C Phillips; K Woodbridge; G V M Williams; Blackett Lab., Imperial Coll. of Sci., Technol. & Med., London, UK; C C Phillips; Blackett Lab., Imperial Coll. of Sci., Technol. & Med., London, UK; K Woodbridge; Blackett Lab., Imperial Coll. of Sci., Technol. & Med., London, UK
Журнал:
Semiconductor Science and Technology
Дата:
1994-05-02
Аннотация:
Low-temperature time-resolved degenerate four-wave mixing (DFWM), single-beam excite/probe and transient grating measurements have been performed on In<sub>x</sub>Ga<sub>1-x</sub>As/GaAs superlattices with thin ( approximately 6 nm) In<sub>x</sub>Ga<sub>1-x</sub>As wells. We find weak dephasing of heavy-hole (hh) excitons by acoustic phonons. The hh exciton homogeneous linewidth temperature coefficient is 1.9+or-1 mu eV K<sup>-1</sup>. The low-temperature hh exciton optical nonlinearity is successfully modelled in terms of exciton phase-space filling and exchange interactions in the hh exciton gas. From low-temperature transient grating measurements we find hh exciton in-plane mobilities as high as 6.7*10<sup>4</sup> cm<sup>2</sup> V<sup>-1</sup> s<sup>-1</sup> and mobilities which are greater in superlattices with thinner barriers.
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