INDIRECT-TO-DIRECT CROSSOVER OF LATERALLY CONFINED EXCITONS IN COUPLED QUANTUM-WELLS

Lateral confinement of excitons in coupled double quantum wells can be tailored to control exciton interwell tunneling. An indirect exciton in a coupled asymmetric double quantum well under applied bias can be made a direct exciton by lateral confinement. Large changes in exciton ground-state energies and oscillator strengths occur at this crossover. This crossover provides a new signature for lateral-confinement effects on excitons in zero-dimensional nanostructures such as quantum dots and electron-hole double-layer systems in a strong magnetic field.