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

The electron carrier density, the electron mobility, and the electron effective mass in modulation-doped GaAsrIn0.18Ga0.82AsrAl0.25Ga0.75As 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 In0.18Ga0.82As quantum wells, and the fast Fourier transformation results for the S–dH data clearly indicate the electron occupation of one sub-band in the GaAsrIn0.18Ga0.82GarAl0.25Ga0.75As single quantum wells. The electron carrier density and the effective mass determined from the temperature dependent S–dH measurements were 2.04=1012 cmy2 and 0.0703 m0, respectively. The electronic sub-band energies, the corresponding wave functions, and the Fermi energies in the In0.18Ga0.82As 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 GaAsrIn0.18Ga0.82AsrAl0.25Ga0.75As single quantum wells hold promise for potential applications in electronic devices such as high-speed field-effect transistors. q1999 Elsevier Science B.V. All rights reserved