Heating of two-dimensional excitons by nonequilibrium acoustic phonons

The energy distribution functions of two-dimensional excitons in the presen ce of nonequilibrium acoustic phonons have been calculated for the geometry used in heat-pulse experiments. The results were obtained by solving numer ically the kinetic equation for the case where the exciton gas equilibrates with phonons during its lifetime. The cases of the low and high exciton-ga s density limits are considered. It is shown that at low exciton-gas densit ies the distribution does not follow the Boltzmann function and depends on the quantum-well width. A comparison with earlier experimental data is made . (C) 1999 American Institute of Physics. [S1063-7834(99)03609-6].