6533b836fe1ef96bd12a130e

RESEARCH PRODUCT

Tuning the exciton luminescence in an acoustically depleted two-dimensional electron gas

subject

description

Standing-wave piezoelectric fields can be used to vary spatially and temporally charge conditions in $\mathrm{Ga}\mathrm{As}∕\mathrm{Al}\mathrm{Ga}\mathrm{As}$ quantum wells (QWs), offering a versatile tool to control the two-dimensional electron gas (2DEG) density in the well. A $\mathrm{Li}\mathrm{Nb}{\mathrm{O}}_{3}$ piezoelectric resonator imparts a MHz-frequency oscillating piezoelectric field with a controllable ratio of the in-plane and the vertical field components to a 2DEG placed in close proximity to the plate surface. This allows us to dynamically tune the charge state in the plane of the QW and to influence the photoluminescence spectra. It is found that spatially distributed regions of depleted and accumulated electron densities are formed in the QW plane due to the in-plane components of the piezoelectric field. The photoluminescence spectrum then varies both spatially and temporally, exhibiting an electron-hole plasma recombination at large electron densities and exciton and trion emissions at the extreme of small densities. Controlling the piezoelectric field component perpendicular to the QW layers allows us to achieve the spatially indirect exciton luminescence in double quantum well structures.