TRANSMISSION IN COMPOSITIONALLY NONABRUPT GaAs/Al_xGa_(1-x)As HETEROJUNCTIONS: BEYOND THE CONSTANT INTERFACIAL EFFECTIVE-MASS APPROXIMATION

摘要

The transmission properties of compositionally nonabrupt GaAs/Al_xGa_(1-x)As heterojunctions are calculated by taking into account the spatial dependence of the carrier effective mass through the nonabrupt interface. The description of the nonabrupt heterojunctions is obtained with the assumption of a linear aluminium molar fraction variation in the interface. A multistep technique is used for the numerical solution of the Hamiltonian with a space dependent effective mass. The linear spatial dependence of the effective mass through the interface changes the transmission properties of compositionally nonabrupt GaAs/Al_xGa_(1-x)As heterojunctions in comparison with those obtained with the constant effective mass approximation. The absence of resonant peaks for large interface widths is shown for electrons and holes, in disagreement with a prior prediction of their existence.