Dependence of resonant tunneling current on Al mole fractions in AlxGa1−xAs-GaAs-AlxGa1−xAs double barrier structures

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Electron transport in AlxGa1−xAs-GaAs-AlxGa1−xAs double barrier tunneling structures is studied as a function of Al content x in the barrier for the case where the thickness of the barrier is 11 atomic layers and that of the GaAs well layer is 7 nm. It is shown that the density JRT of resonant tunneling current varies systematically from 7.0×102 to 3.5×104 A cm−2 as x is varied from 1.0 to 0.43. These data are found to be quantitatively explained by the theoretical calculation, in which the band discontinuity at Γ valley is taken as the barrier height. This result indicates that the electron tunneling through the double barrier structure is dominated by the barrier height of Γ minimum even when the subsidiary minima have lower energies (0.45≤x≤1.0).