PHOTOLUMINESCENCE OF THE ELECTRON-DRESSED CONFINED X(-) EXCITON IN ANN-TYPE ALAS GAAS RESONANT-TUNNELING DEVICE/

Spectroscopic evidence is presented for the existence of the electron- dressed exciton (X(-))-an electron bound to an exciton-in the 8-nm-wid e quantum well of an asymmetric n-type AlAs/GaAs triple-barrier resona nt tunnelling device. This is revealed by a transition just below the lowest heavy-hole exciton, leading to a doublet structure in the photo luminescence peak. The splitting of 2.1 meV is only weakly dependent o n electrical bias. The effect is observed in the neighborhood of each of the three electron current resonances, when the number of electrons in the well is still low but significantly greater than that of photo created holes. The influence on the X(-) spectrum of applied electrica l bias, temperature, excitation photon energy, and excitation power de nsity is investigated. Indications were also found for the existence o f X(-) in the narrower, 6-nm-wide quantum well.