TIME-RESOLVED MAGNETOPHOTOLUMINESCENCE MEASUREMENTS OF THE INTEGER QHE, FRACTIONAL QHE AND EXTREME QUANTUM LIMIT

Low-temperature, time-resolved magneto-photoluminescence (TRPL) measurements of 2D electron-free-valence-hole recombination have been carried out in the IQHE, FQHE and magnetically induced electron solid regimes of a GaAs/AlGaAs single heterojunction. Clear differences, not present at elevated temperatures, are found in the measured PL decay time (approximately 1 ns) for components of multiple-peak structure observed beyond nu = 1/5 used previously to construct a phase diagram associated with the Wigner solid. The new TRPL results and earlier PL data, taken together, are consistent with a mechanism in which the spectral feature associated with crystallisation derives from the trapping of excitons within a few Bohr radii (z separation) of the heterointerface and their subsequent (x, y) localisation by the presence of a 2D electron system with a degree of spatial order at this interface.