X-point tunneling in AlAs–GaAs–AlAs double barrier heterostructures

The dynamics of X-point tunneling in AlAs–GaAs–AlAs double barrier heterostructures is studied with numerical simulation. The problem is formulated within the framework of the one-band Wannier orbital model which allows for simultaneous descriptions of the Gamma-point double barrier profile and the X-point double well profile in this heterostructure. Time dependences of the following processes are illustrated: (i) resonant tunneling of Gamma-valley electron packets via the X-point quantum well states localized in the AlAs layers, (ii) nonresonant tunneling of Gamma-electron packets (with energy below the AlAs Gamma-point barrier) through the X-point continuum states, and (3) resonant tunneling via Gamma-X mixed quantum well states localized in both the GaAs Gamma-point quantum well and the AlAs X-point double quantum well. In addition, the effects of X-point tunneling on the escape times of electrons localized in the GaAs quantum wells are examined.