Measurement of the exciton-formation time and the electron- and hole-tunneling times in a double-quantum-well structure

The bimolecular nature of exciton formation from free carriers is demonstrated experimentally in a GaAs asymmetric double-quantum-well tunneling structure. A bimolecular formation coefficient of 6×${10}^{\mathrm{-}12}$ ${\mathrm{cm}}^2$/ps is obtained. The electron- and hole-tunneling times are determined simultaneously under the same sample conditions.