Resonant tunneling through X-valley states in GaAs/AlAs/GaAs single-barrier heterostructures

Clear negative differential resistance has been observed in a GaAs/AlAs/GaAs single-barrier heterostructure due to the presence of a quasi-bound state associated with the X-point profile. This surprising result is due to the fact that although the Γ-point profile of this heterostructure is a simple single tunneling barrier, the X-point profile actually constitutes a quantum well some 0.3 eV deep lying about 0.2 eV above the Γ point of GaAs. The experimental evidence is a sharp cutoff in conductance at about 0.36 V bias, characteristic of tunneling via a confined state.