Transmission in symmetrical GaAs/AlxGa1-xAs double-barriers with compositionally nonabrupt interfaces

Abstract Transmission properties of electrons through GaAs/AlxGa1-xAs symmetrical double-barriers with abrupt and nonabrupt interfaces are calculated and compared. The interface potential and carrier effective-mass are obtained assuming a linear variation of the aluminium molar fraction in the transition regions GaAs ⇔ AlxGa1-xAs. When the electron energy E0,-1,e is smaller than the double-barrier height Vx0 , changes in the internal interfaces widths shift tunneling resonances, while changes in the external interfaces increase the energy widths of the resonant transmission peaks. When E0,-1,e > Vx0, both external and internal interfaces modify remarkably the transmission of nonabrupt GaAs/AlxGa1-xAs double-barriers when compared with the abrupt double-barrier, even if their widths are as small as two GaAs lattice parameters. However, the first transmission peaks of abrupt and nonabrupt GaAs/AlxGa1-xAs double-barriers are very similar, except when the interface widths are greater than four lattice parameters.