Applications of ultrafast terahertz pulses for intra-excitonic spectroscopy of quasi-2D electron-hole gases

Robert A. Kaindl, Marc A. Carnahan, Daniel Hägele, D. S. Chemla

Research output: Contribution to journalArticlepeer-review

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 languageEnglish (US)
Pages (from-to)83-89
Number of pages7
JournalJournal of Nanoelectronics and Optoelectronics
Volume2
Issue number1
DOIs
StatePublished - 2007

Keywords

  • Excitons
  • Low-Dimensional Semiconductors
  • TeraHertz Spectroscopy
  • Ultrafast Processes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering

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