Electron-hole separation in a two-dimensional electron system induced by electric fields

Electric-field-induced separation of electrons and holes in a two-dimensional electron system is demonstrated in a single-side-doped GaAs/GaA1As quantum well structure. The separation is manifest in the quantum-confined Stark shift and also in a reduced electron-hole overlap that produces a large increase in the radiative recombination time. These effects were produced either by applying a gate voltage or by changing the internal Hartree electric field via changing the electron density. The observed order-of-magnitude lifetime increase agrees quantitatively with results of self-consistent calculations of the wavefunction overlaps.