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Applications of Ultrafast Terahertz Pulses for Intra-ExcitonicSpectroscopy of Quasi-2D Electron-Hole Gases

Journal Article · · Journal of Nanoelectronics and Optoelectronics
OSTI ID:917541
Excitons are of fundamental interest and of importance foropto-electronic applications of bulk and nano-structured semiconductors.This paper discusses the utilization of ultrafast terahertz (THz) pulsesfor the study of characteristic low-energy excitations of photoexcitedquasi 2D electron-hole (e-h) gases. Optical-pump THz-probe spectroscopyat 250-kHz repetition rate is employed to detect characteristic THzsignatures of excitons and unbound e-h pairs in GaAs quantum wells.Exciton and free-carrier densities are extracted from the data using atwo-component model. We report the detailed THz response and pairdensities for different photoexcitation energies resonant to heavy-holeexcitons, light-hole excitons, or the continuum of unbound pairs. Suchexperiments can provide quantitative insights into wavelength, time, andtemperature dependence of the low-energy response and composition ofoptically excited e-h gases in low-dimensionalsemiconductors.
Research Organization:
Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
Sponsoring Organization:
USDOE Director. Office of Science. Basic EnergySciences
DOE Contract Number:
AC02-05CH11231
OSTI ID:
917541
Report Number(s):
LBNL--61752; BnR: KC0202020
Journal Information:
Journal of Nanoelectronics and Optoelectronics, Journal Name: Journal of Nanoelectronics and Optoelectronics Journal Issue: 1 Vol. 2
Country of Publication:
United States
Language:
English