Room‐temperature excitonic optical nonlinearities of molecular beam epitaxially grown ZnSe thin films

Large optical nonlinearities have been observed in molecular beam epitaxially grown thin films of ZnSe at room temperature and at T=150 K. A comparison with a plasma theory indicates that in both cases exciton screening is the dominating mechanism for the nonlinearity. The maximum nonlinear index per excited electron‐hole pair at room temperature is comparable to that of bulk GaAs and GaAs‐AlGaAs multiple quantum wells. The measured absorption and nonlinear index spectra agree quite well with our calculated values.