OPTICAL MEASUREMENT OF THE AMBIPOLAR DIFFUSION LENGTH IN A ZNCDSE-ZNSE SINGLE-QUANTUM-WELL

We describe a straightforward technique for the measurement of carrier diffusion in semiconductors. Using an optical microscope we can spati ally image luminescence with a resolution of similar to 500 nm. We mea sured the ambipolar diffusion length in a Zn0.75Cd0.25Se-ZnSe single q uantum a well by fitting the spatially resol ed luminescence profile w ith the solution of the two-dimensional diffusion equation. The ambipo lar diffusion length was found to be 498 nm at a carrier density of si milar to 1 x 10(18) cm(-3) and we deduce an ambipolar diffusion consta nt of 1.7 cm(2) s(-1). (C) 1997 American Institute of Physics.