Real-time dynamics of the acoustically driven electron–hole transport in GaAs quantum wires

Sidewall Quantum Wires on GaAs (001) Substrates

“…A metal stripe was deposited at the end of the QWR (at y = 90 µm) to block the acoustic transport. Since the depth of the QWR (below a 200 nm AlGaAs barrier) is much smaller than the SAW wavelength (λ SAW = 5.6 µm), the metal efficiently screens the SAW piezoelectric potential at the depth of the QWR and induces the recombination of the carriers transported by the SAW field [19]. In the ideal case, one thus expects to observe PL at two positions along the SAW path: (i) at the excitation location, where non-transported carriers recombine and (ii) at the metal stripe position due to recombination of transported carriers.…”

“…Their optical and transport properties were found, however, to be very sensitive to potential fluctuations along the transport path. These fluctuations create trapping centers, which can capture charge carriers during the acoustic driven am- bipolar transport and induce their recombination, thus resulting in a reduction of the acoustic transport efficiency [19].…”

Atoms riding Rayleigh waves

“…Surface acoustic waves (SAW) in semiconductors can trap electrons and holes in their deformation potential and carry them along the surface. This phenomenon, known as the acoustoelectric effect or acoustoconductance, was recognized about two decades ago [1][2][3][4][5][6][7] and exploited in various applications, ranging from optoelectronic systems [8,9] to singleelectron transport [10,11] and quantum computation [12][13][14][15]. Although in these works SAWs are generated by external sources, surface electrons can also be trapped by a surface phonon that the electron itself has excited with its Coulomb field (self-trapping) [16].…”