Paper NM-TuP2
Influence of Electron Interference Effects on Reflection of Electron Waves From Potential Barrier in 2D Semiconductor Nanostructures

Tuesday, December 13, 2016, 4:00 pm, Room Mauka

The influence of the interference of electron waves in the case of their reflection from potential barrier on the spatial distribution of the density of quantum-mechanical current ej_х(x,z) (e – electron charge) in 2D semiconductor nanostructure which is represented by rectangular narrow ( x < 0,QW₁) and wide (x > 0, QW₂) quantum wells ( QWs) sequentially oriented along the direction of the propagation of electron wave has been studied theoretically. It is supposed that the wave falls from the narrow QW₁ on the semi-infinite potential barrier V₀ in height in the wide QW₂, the energy of the falling wave being less than V₀. Differing widths of QW₁ and QW₂ provide the non-orthogonality of wave functions of particles in these regions and the corresponding existence of electron interferential effects in this kind of nanostructure. In particular cases these effects lead to the appearance of spatially inhomogeneous distributions еj_x⁽¹⁾(x,z) in QW₁ and еj_x⁽²⁾(x,z) in QW₂. It has been analytically demonstrated that in case of an electron wave falling along the first (lower) quantum-dimensional subband in QW₁ and its kinetic energy E_x being less than the energy positions of all the other subbands in QW₁ (i.e., the undamped propagation of the wave reflected from the barrier with real quasi-momentum is possible only along this lower subband) еj_x⁽¹⁾(x,z) and еj_x⁽²⁾(x,z) are equal to zero. However, if a particle has such an energy that the refection of the wave with real quasi-momenta is possible along more than one (lower) subband, then the situation completely changes due to the interference of the reflected waves. In this case the interference leads to an existence of a complicatedly oscillating spatially inhomogeneous distribution еj_x⁽¹⁾(x,z), and under the barrier in QW₂ it provides the appearance of exponentially damped at х→∞ and possessing a coordinate dependence of leakage еj_x⁽²⁾(x,z) under the barrier. Besides, three regions of the symmetric along z axis propagation еj_x⁽²⁾(x,z) are formed under the barrier. They are the central one, in which the current is directed in axis x positive direction, and two side regions in which the current is directed in negative direction. The presence of the regions of that kind provides the charge flow from under the barrier. The numerical calculations of еj_x⁽¹⁾(x,z) and еj_x⁽²⁾(x,z) have also been made taking into account 31 subbands. It should be noted that these kinds of effects have a general nature and exist in 1D and 2D nanostructures with arbitrary profiles of QWs and barriers.