  A comprehensive experimental investigation of exciton and biexciton
recombination in GaAs/AlGaAs quantum wells is presented. Exciton and biexciton
recombination times are found to be 16 and 55 ps, respectively. A method of
determining the dynamics of the exciton temperature is developed. It is shown
that both exciton and biexciton recombination processes increase the exciton
temperature by an amount as high as $\sim 10$ K. These processes impose a new
restriction on the possibility of exciton Bose-Einstein condensation and make
impossible its achievement in a system of direct excitons in GaAs quantum wells
even for resonantly excited exciton gas.
