INVESTIGATION OF PHOTOELECTRICAL PROPERTIES AND CARRIER TRANSPORT IN POROUS SILICON STRUCTURES BY THE TRANSIENT GRATING TECHNIQUE

The light-induced transient grating technique is combined to study pho toelectrical properties of porous silicon sublayers with different str uctures in an optical way. This technique based on the measurements of a diffracted beam in the dark field ensures its sensitivity is higher than the techniques of differential absorption used for porous Si stu dies. Carrier diffusion and light absorption coefficients at 1.06 mu m of the lower layer of porous Si structures have been found similar to those in crystalline substrate. The free-standing films at high injec tion levels indicated fast non-equilibrium carrier recombination with a subnanosecond time.