Electron occupation in subbands dependent on the indium mole fraction in [formula omitted] one-side-modulation-doped quantum wells

Abstract

Shubnikov-de Haas (S-dH) and Van der Pauw Hall-effect measurements on In 0.53 Ga 0.47 As In 0.52 Al 0.48 As and In 0.65Ga 0.35 As In 052 Al 0.48 As one-side-modulation-doped quantum wells grown by metalorganic chemical vapor deposition have been carried out to investigate the magnetotransport properties of an electron gas and to determine the subband energies and wave functions in single quantum wells. Transmission electron microscopy measurements showed that the In 0.53 Ga 0.47 As In 0.52 Al 0.48 As heterointerfaces have a perfect lattice match and that the In 0.65 Ga 0.35 As In 0.52 Al 0.48 As heterointerfaces have a small lattice mismatch. The Shubnikov-de Haas measurements at 1.5 K demonstrated clearly the existence of a two-dimensional electron gas in the quantum wells. The fast Fourier transformation results for the S-dH data indicated clearly electron occupation of two and three subbands in the In 0.53Ga 0.47As and In 0.65Ga 0.35As single quantum wells, respectively. Electronic subband energies and wavefunctions in the quantum wells were calculated by a self-consistent method using the transfer matrix method based on the envelope-function approximation. These results indicate that the In x Ga 1− x As quantum well with the smaller energy gap has more electron occupation in the subband levels.