DIELECTRIC FUNCTION-THEORY CALCULATIONS OF POLARITONS IN GAN

Properties of polaritons (free excitons coupled with photons of simila r energy) in gallium nitride are investigated by performing calculatio ns based on dielectric function theory including all three excitons A, B and C (characteristic for the wurtzite structure). Moreover the exc ited states of excitons have been taken into account by adding Elliott 's components to dielectric function. Energies, polarizabilities and d amping constants of excitons are determined. It is shown that due to i nter-exciton interactions the B and C excitons are strongly damped. It is estimated that the characteristic time of B to A relaxation is t(B A) = 1 ps. The exciton C lifetime is estimated tau(c) = 0.2 ps.