Influence of the X-valley on the tunneling and lifetime of electrons in GaAs/AlAs heterostructures

The effective-mass approximation is used to calculate the probability for tunneling of an electron through a triangular barrier and its lifetime in the triangular quantum well formed by a GaAs/AlAs heterojunction and a strong electric field. It is shown that for such structures the tunneling probability into the X-valley can exceed the probability for tunneling into the Γ-valley by several orders of magnitude. The lifetime of an electron in the quasistationary state formed by the triangular heterobarrier is also essentially determined by tunneling to the X-valley and comes to ∼10−13–10−11 s in fields E∼105–106 eV/cm.