Voltage tunable potential wells for wire confinement of excitons

Abstract

We use applied voltage to modulate lateral strain in a quantum well, thereby achieving tunable confinement of excitons. A capacitor structure is fabricated by attaching a flexible film containing a quantum well and a conducting layer to a doped Si substrate patterned with raised ribs. The film conforms to the ribs, creating a potential well for excitons where the quantum well is in tension. The film is pulled toward the substrate through electrostatic force, increasing the confinement. Modulation of strain confinement by over 50% is reported. The effect is reversible with voltage and polarity independent, as expected for electrostatic attraction.