G. Finkelstein et al., NEGATIVELY AND POSITIVELY CHARGED EXCITONS IN GAAS ALXGA1-XAS QUANTUM-WELLS/, Physical review. B, Condensed matter, 53(4), 1996, pp. 1709-1712
We report the observation of the positively charged exciton and of the
triplet state of the negatively charged exciton in modulation doped G
aAs quantum wells. Applying a gate voltage at high magnetic fields we
find that the photoluminescence line of the two-dimensional electron g
as smoothly transforms into a negatively charged exciton and not into
a neutral exciton. The Zeeman splitting of this line exhibits an abrup
t change at the metal-insulator transition.