RESUMEN
Single-electron sources, formed by a quantum dot (QD), are key elements for realizing electron analogue of quantum optics. We develop a new type of single-electron source with functionalities that are absent in existing sources. This source couples with only one lead. By an AC rf drive, it successively emits holes and electrons cotraveling in the lead, as in the mesoscopic capacitor. Thanks to the considerable charging energy of the QD, however, emitted electrons have energy levels a few tens of millielectronvolts above the Fermi level, so that emitted holes and electrons are split by a potential barrier on demand, resulting in a rectified quantized current. The resulting pump map exhibits quantized triangular islands, in good agreement with our theory. We also demonstrate that the source can be operated with another tunable-barrier single-electron source in a series double QD geometry, showing parallel electron pumping by a common gate driving.
RESUMEN
Here, we describe the band-bending situation for introducing electrons in an undoped GaAs and AlGaAs quantum well. Our calculation has shown that an externally applied electric field can modulate two-dimensional electron gas (2DEG) without standard modulation doping. The topic of electrically modulated 2DEG has only background impurities, no intentional dopants, so scattering or dephasing by background potential fluctuations should be much reduced. Using our calculation, it is straightforward to confine carriers (in the range of 1010~1011 cm-2), when the external electric field is more than threshold voltage, 4 V to the surface metal gate.
