Abstract

Optical induced concentration gratings has been extensively used to determine the ambipolar diffusion coefficient in bulk¹ and quantum well² semiconductors. These gratings are based on the spatial modulation of equal numbers of excess electrons and holes across the excitation region. They are optically induced in the sample by the interference of two laser pulses with parallel polarisation. Monitoring the grating decay for different grating periods allows the determination of the ambipolar diffusion coefficient. This coefficient is dominated by the motion of the slower carriers, i.e. holes, and gives no accurate information about the faster electron motion.

© 1996 Optical Society of America