The dependence of the carrier density and the mobility on the spacer-layerthickness in modulation-doped AlxGa1-xAs/InyGa1-yAs/GaAs asymmetric singlequantum wells

Citation
M. Jung et al., The dependence of the carrier density and the mobility on the spacer-layerthickness in modulation-doped AlxGa1-xAs/InyGa1-yAs/GaAs asymmetric singlequantum wells, APPL SURF S, 177(1-2), 2001, pp. 1-7
Citations number
23
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science","Material Science & Engineering
Journal title
APPLIED SURFACE SCIENCE
ISSN journal
0169-4332 → ACNP
Volume
177
Issue
1-2
Year of publication
2001
Pages
1 - 7
Database
ISI
SICI code
0169-4332(20010601)177:1-2<1:TDOTCD>2.0.ZU;2-2
Abstract
The variation of the electron carrier occupation and the mobility in the su bband as a function of the spacer layer thickness in modulation-doped AlxGa 1-xAs/InyGa1-yAs/GaAs strained single quantum wells was investigated by Shu bnikov-de Haas (S-dH) and Van der Pauw Hall-effect measurements. The result s of the fast Fourier transform (FFT) for the S-dH data and those of the Ha ll-effect data showed that the magnitude of the electron carrier density in the sub-band increased as the spacer layer became thinner, and the increas e in the carrier density with decreasing spacer-layer thickness resulted fr om an increase in the distance between the Fermi energy level and the top o f the depletion layer. The full width at half maxima of the FFT results for the S-dH data and of the results of the Hall-effect measurements indicated that the value of the electron mobility increased as the spacer-layer thic kness increased, and the increase in the electron mobility originated from a decrease in the Coulomb interaction between the ionized donors and the el ectrons, The electronic sub-band energies, corresponding wave functions, an d the Fermi energies in the InyGa1-yAs quantum wells were calculated by a s elf-consistent method taking into account exchange-correlation effects toge ther with the strain and nonparabolicity effects. These present results can help to improve the understanding for the application of AlxGa1-xAs/InyGa1 -yAs/GaAs strained single quantum wells in electronic devices such as high- frequency and high-speed field-effect transistors. (C) 2001 Elsevier Scienc e B.V. All rights reserved.