ANALYSIS OF THE EXCITONIC MOTT TRANSITION IN GASE

Detailed photoluminescence spectra of GaSe at a bath temperature of 2K were measured at electron-hole densities ranging from below to above the screening limit for the free direct excitons. Special care was used to reduce the effects of spatial carrier inhomogeneity. We observe a continuous transition from exciton recombination processes to an e-h plasma emission. We compare our observations with the results of a simplified first order theory which accounts for electron-hole correlation effects. The observed red shift of the fundamental direct exciton level is well reproduced by our theoretical calculations.