We study the pumping effects, in both the adiabatic and nonadiabatic regimes, of a pair of finite finger-gate array (FGA) on a narrow channel. Connection between the pumping characteristics and associated mechanisms is established. The pumping potential is generated by ac biasing the FGA pair. For a single pair (N = 1) of finger gates (FG's), the pumping mechanism is due to the coherent inelastic scattering of the traversing electron to its subband threshold. For a pair of FGA with pair number N > 2, the dominant pumping mechanism becomes that of the time-dependent Bragg reflection. The contribution of the time-dependent Bragg reflection to the pumping is enabled by breaking the symmetry in the electron transmission when the pumping potential is of a predominant propagating type. This propagating wave condition can be achieved both by an appropriate choice of the FGA pair configuration and by the monitoring of a phase difference φ between the ac biases in the FGA pair. The robustness of such a pumping mechanism is demonstrated by considering a FGA pair with only pair number N = 4.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - 1 Aug 2004|