Applications of Ultrafast TeraHertz Pulses for Intra-Excitonic Spectroscopy of Quasi-2D Electron–Hole Gases
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.
Keywords: EXCITONS; LOW-DIMENSIONAL SEMICONDUCTORS; TERAHERTZ SPECTROSCOPY; ULTRAFAST PROCESSES
Document Type: Research Article
Publication date: 01 April 2007
- Journal of Nanoelectronics and Optoelectronics (JNO) is an international and cross-disciplinary peer reviewed journal to consolidate emerging experimental and theoretical research activities in the areas of nanoscale electronic and optoelectronic materials and devices into a single and unique reference source. JNO aims to facilitate the dissemination of interdisciplinary research results in the inter-related and converging fields of nanoelectronics and optoelectronics.
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