  Generation-recombination interband transitions via acoustic phonons are
allowed in a disordered graphene because of violation of the energy-momentum
conservation requirements. The generation-recombination processes are analyzed
for the case of scattering by a short-range disorder and the deformation
interaction of carriers with in-plane acoustic modes. The
generation-recombination rates were calculated for the cases of intrinsic and
heavily-doped graphene at room temperature. The transient evolution of
nonequilibrium carriers is described by the exponential fit dependent on doping
conditions and disorder level. The characteristic relaxation times are
estimated to be about 150 - 400 ns for sample with the maximal sheet resistance
~5 kOhm. This rate is comparable with the generation-recombination processes
induced by the thermal radiation.
