ON A SIMPLIFIED ANALYSIS OF THE EFFECTIVE ELECTRON MASS IN ULTRATHIN FILMS OF NONPARABOLIC SEMICONDUCTORS IN THE PRESENCE OF A PARALLEL MAGNETIC-FIELD

An attempt is made to study the effective electron mass at the Fermi l evel in ultrathin films of nonparabolic semiconductors in the presence of a parallel magnetic field on the basis of a newly derived electron dispersion law. It is found, taking n-Hg1-xCdxTe and In1-xGaxAsyP1-y lattice matched to InP as examples, that the effective Fermi level mas s depends on the subband index in addition to the Fermi energy due to the presence of the magnetic field. The effective masses corresponding to different subbands increase with increasing surface electron conce ntration and decreasing film thickness. Besides, the numerical values of the masses in quaternary alloys are smaller than those for ternary semiconductors. In addition, the corresponding well-known results of u ltrathin films of nonparabolic semiconductors in the absence of the ma gnetic field are also obtained as special cases of our generalized for mulation under certain limiting conditions.