Trion and exciton dephasing measurements in modulation-doped quantum wells: A probe for trion and carrier localization

To investigate the properties of a two-dimensional carrier gas at intermedi ate densities, we perform picosecond transient four-wave mixing experiments on trions (charged excitons) and neutral excitons in modulation p-doped Cd Te/Cd1-x-yMgxZnyTe quantum wells. The determination of trion and exciton de phasing rates reveals a localization of both trions and holes in potential fluctuations induced by the ionized remote accepters. We demonstrate that t rions can be efficiently used as a charged optical probe sensitive to elect rostatic potential fluctuations which are imperceptible for neutral exciton s. [S0163-1829(99)15731-X].