Electronic subbands in InxGa1-xAs/InyAl1-yAs pseudomorphic heterostructures grown by GSMBE

In this paper, we report our investigations on the subband structures of tw o dimensional electron gases in pseudomorphic In0.8Ga0.2As/In0.53Ga0.47As/I nAlAs/InP modulation doped heterostructures grown by gas source molecular b eam epitaxy. Shubnikov-de Haas (SdH) oscillation and quantum Hall effect me asurements reveal that there are two subbands populated in the studied modu lation doped system. The electron densities of the 0th and the Ist subband are 2.84 x 10(12) cm(-2) and 3.4 x 10(11) cm(-2), respectively. A longer qu antum Lifetime of the electrons in the 0th subband than that in the Ist sub band has been observed. The effective masses of the two subbands determined by the field-dependent cyclotron resonance measurements are (0.061 +/- 0.0 01)m(0) for the 0th subband and (0.049 +/- 0.001)mo for the 1th subband, re spectively. The energy differences between the Fermi level and the lowest s ubband minima have been calculated from the measured electron densities and effective masses, which are 111.6 meV and 16.5 meV.