Determination of the carrier density and the effective mass of the two-dimensional electron gas in asymmetric GaAs/In 0.18Ga 0.82As/Al 0.25Ga 0.75As modulation-doped strained single quantum wells

Abstract

The electron carrier density, the electron mobility, and the electron effective mass in modulation-doped GaAs/In 0.18Ga 0.82As/Al 0.25Ga 0.75As strained single quantum wells were investigated by Shubnikov–de Haas (S–dH) and Van der Pauw Hall-effect measurements at 1.5 K. The angular dependent S–dH measurements at 1.5 K demonstrated clearly the existence of a quasi-two-dimensional electron gas in the In 0.18Ga 0.82As quantum wells, and the fast Fourier transformation results for the S–dH data clearly indicate the electron occupation of one sub-band in the GaAs/In 0.18Ga 0.82Ga/Al 0.25Ga 0.75As single quantum wells. The electron carrier density and the effective mass determined from the temperature dependent S–dH measurements were 2.04×10 12 cm −2 and 0.0703 m 0, respectively. The electronic sub-band energies, the corresponding wave functions, and the Fermi energies in the In 0.18Ga 0.82As quantum wells were calculated by a self-consistent method taking into account exchange-correlation effects together with the strain and non-parabolicity effects. These results indicate that GaAs/In 0.18Ga 0.82As/Al 0.25Ga 0.75As single quantum wells hold promise for potential applications in electronic devices such as high-speed field-effect transistors.