Photon Emission from GaAs in Thermal Equilibrium. At room temperature, the intrinsic concentration of electrons and holes in GaAs is n; ~ 1.8 x 10 cm-3. The radiative electron- hole recombination coefficient r ~ 10-10 cm3/s under certain conditions. Find the following: 1. The electroluminescence rate ( photon flux concentration) (photons/cm3-s). 2. The photon-flux density o (photons/cm2-s) for a 2-micrometer-thick layer of GaAs. 3. The emitted intensity (W/cm2)