CARRIER DENSITY-DEPENDENCE OF THE AMBIPOLAR DIFFUSION-COEFFICIENT IN GAAS N-I-P STRUCTURES

We report on investigations of the ambipolar diffusion coefficient in GaAs n-i-p structures in which the electron density in the n channel i s varied. The ambipolar diffusion coefficient was determined by time-r esolved diffusion experiments of the Shockley-Haynes type. The depende nce of the ambipolar diffusion coefficient on the varying carrier dens ity is in excellent agreement with the theory of ambipolar diffusion i n n-i-p-i systems. In the investigated sample, the ambipolar diffusion coefficient reaches a maximum value of 16 300 cm(2)/s. Although the a mbipolar diffusion constant declines with decreasing carrier density, it is in a wide range of the carrier density more than two orders of m agnitude enhanced compared to bulk materials. (C) 1997 American Instit ute of Physics.