Coherent intersubband oscillations in modulation-doped quantum wells

Author

Bao, J. ; Merlin, R. ; Pfeiffer, L.N. ; West, K.W.

Author_Institution

Dept. of Phys., Michigan Univ., Ann Arbor, MI, USA

fYear

2001

fDate

11-11 May 2001

Firstpage

248

Lastpage

249

Abstract

Summary form only given. We report on the observation of coherent intersubband beats in time-domain femtosecond experiments on a high-mobility two-dimensional electron gas. The sample is a 400-/spl Aring/ one-sided modulation-doped GaAs-AlGaAs single quantum-well grown by molecular beam epitaxy. The top Al/sub 0.2/Ga/sub 0.8/As layer contains Si donors which are separated from the GaAs quantum well by a thick undoped space layer. The areal density of the electron gas at the interface is /spl rho/ /spl ap/ 2 /spl times/ 10/sup 11/ cm/sup -2/ and the low-temperature mobility is 1.2 /spl times/ 10/sup 6/ cm/sup 2//Vs. After removal of the substrate, pump-probe experiments were performed at /spl sim/ 7 K in the transmission geometry using a modelocked Ti-sapphire laser. The central wavelength of the pulses was tuned to resonate with excitons associated with heavy-hole states at /spl sim/ 800 nm.

Keywords

III-V semiconductors; aluminium compounds; electron mobility; gallium arsenide; high-speed optical techniques; molecular beam epitaxial growth; optical pumping; oscillations; semiconductor quantum wells; two-dimensional electron gas; 2D electron gas; 800 nm; Al/sub 0.2/Ga/sub 0.8/As; GaAs quantum well; GaAs-AlGaAs; GaAs-AlGaAs single quantum-well; Si donors; areal density; coherent intersubband oscillations; excitons; heavy-hole states; high-mobility two-dimensional electron gas; low-temperature mobility; modulation-doped quantum wells; molecular beam epitaxy; probe pulses; pump-probe experiments; substrate; time-domain femtosecond experiments; transmission geometry; undoped space layer; Electron mobility; Epitaxial layers; Gallium arsenide; Geometrical optics; Laser excitation; Molecular beam epitaxial growth; Quantum wells; Solid modeling; Substrates; Time domain analysis;

fLanguage

English

Publisher

ieee

Conference_Titel

Quantum Electronics and Laser Science Conference, 2001. QELS '01. Technical Digest. Summaries of Papers Presented at the

Conference_Location

Baltimore, MD, USA

Print_ISBN

1-55752-663-X

Type

conf

DOI

10.1109/QELS.2001.962202

Filename

962202