Abstract
Excitons are of fundamental interest and of importance for opto-electronic applications of bulk and nano-structured semiconductors. This paper discusses the utilization of ultrafast terahertz (THz) pulses for the study of characteristic low-energy excitations of photoexcited quasi-2D electron-hole (e-h) gases. Optical-pump THz-probe spectroscopy at 250-kHz repetition rate is employed to detect characteristic THz signatures of excitons and unbound e-h pairs in GaAs quantum wells. Exciton and free-carrier densities are extracted from the data using a two-component model. We report the detailed THz response and pair densities for different photoexcitation energies resonant to heavy-hole excitons, light-hole excitons, or the continuum of unbound pairs. Such experiments can provide quantitative insights into wavelength, time, and temperature dependence of the low-energy response and composition of optically excited e-h gases in low-dimensional semiconductors.
Original language | English (US) |
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Pages (from-to) | 83-89 |
Number of pages | 7 |
Journal | Journal of Nanoelectronics and Optoelectronics |
Volume | 2 |
Issue number | 1 |
DOIs | |
State | Published - 2007 |
Externally published | Yes |
Keywords
- Excitons
- Low-Dimensional Semiconductors
- TeraHertz Spectroscopy
- Ultrafast Processes
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Electrical and Electronic Engineering