Optical phonon-assisted ultrafast relaxation of hot carriers: electric field effects

Vishal Saxena; J. P. Evans

doi:10.1117/12.470432

11 June 2002 Optical phonon-assisted ultrafast relaxation of hot carriers: electric field effects

Vishal Saxena, J. P. Evans

Proceedings Volume 4643, Ultrafast Phenomena in Semiconductors VI; (2002) https://doi.org/10.1117/12.470432
Event: Symposium on Integrated Optoelectronic Devices, 2002, San Jose, California, United States

Abstract

The ultra fast relaxation of hot electrons in III-V semiconductors occurs at a time scale of femto-second compared to the relaxation of thermalised electrons that occurs at a time scale of nanosecond. The understanding of this relaxation dynamics is extremely essential for the performance of the ultra-fast multiple quantum well/quantum cascade lasers. Electrons are considered 'hot' when their kinetic energy is much more compared to that of thermalised electrons at the bottom of the conduction band. These hot electrons tend to keep the 'memory' of their momentum anisotropy, which is primarily due to the anisotropy of the band structure of III-V semiconductors. The ultra-fast relaxation of hot electrons is assisted primarily by the interaction with 'LO-optical phonons' (Enery = 36.4meV for GaAs). Hot electrons loose their momentum and spin anisotropy while interacting with optical phonons. During this relaxation process a small fraction of hot electrons recombine optically with the holes available at the acceptor level and their spectroscopy unveils some of the most interesting details of the carrier-relaxation dynamic and the band structure of material. In this paper we present the experimental and computational results of this ultra-fast relaxation phenomenon and also the effect of externally applied high electric field on the relaxation dynamics of these hot carriers.

Citation Download Citation

Vishal Saxena and J. P. Evans "Optical phonon-assisted ultrafast relaxation of hot carriers: electric field effects", Proc. SPIE 4643, Ultrafast Phenomena in Semiconductors VI, (11 June 2002); https://doi.org/10.1117/12.470432

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