The Dependence of the Electron Carrier Occupation in the Subband on the As Mole Fraction in Modulation-Doped InAsxP1—x/InP Strained Single Quantum Wells

Abstract

The variation of the electron carrier occupation in the subband as a function of the As mole fraction and strain effects on the modulation-doped InAsxP1—x/InP single quantum wells have been studied. The results of the fast Fourier transform (FFT) for Shubnikov-de Haas (S-dH) data showed that the magnitude of the electron carrier density in the subband increased as the As mole fraction increased. The full width at half maxima of the FFT results for the S-dH data and the results of the Hall-effect measurements indicated that the value of the electron mobility increased as the As mole fraction increased. The electronic subband energies, the subband energy wavefunctions, the Fermi levels, and carrier densities in the InAsxP1—x quantum wells were calculated by a self-consistent method taking into account the exchange-correlation effects and the nonparabolicity effect together with and without the strain effect. The calculated subband carrier densities which included the strain effect were in more reasonable agreement with those determined from the S-dH and the Hall-effect experiments. The increase of the electron mobility and carrier density with increasing As mole fraction results from the decrease of the electron effective mass and the increase of the conduction band offset, respectivley. In particular, the calculated subband carrier density in the InAs0.6P0.4/InP highly strained quantum well taking into account the strain effect was in very good agreement with that obtained from the measurements.