POROUS SILICON LATERAL SUPERLATTICES

Lateral superlattices in porous silicon layers have been generated. Us ing the photosensitivity of the etching process, periodic stripes are formed not only on the surface but also in the depth of the layer. The modulation depth depends on the illumination wavelength. The periodic ity is obtained from the interference pattern of two laser beams, and can be easily modified by changing the wavelength or the incidence ang les of the beams. The samples formed by this procedure were characteri zed by light diffraction, Two-dimensional structures can also be obtai ned by rotating the sample or by interference of four laser beams. Thi s kind of in-depth lithography and the resulting low-cost fabrication of gratings out of porous silicon offer a wide range of potential appl ications in integrated optics and photonics. (C) 1997 American Institu te of Physics.