A Novel Method for Fabrication of Free Standing Subwavelength Gratings in Gaas/Algaas

We demonstrate a method for the fabrication of suspended gratings in GaAs/AlGaAs. These gratings are designed to act as high reflectivity mirrors in vertical cavity lasers. The fabrication process used is simple, and with a high yield. Stiction or fracture due to surface tension as well as stiction of grating fingers to one another is circumvented. In particular, we found that in fabrication of freestanding GaAs gratings on a submicron scale, wet processes performed after the definition of the gratings greatly reduces the yield. Contrary to the normal fabrication sequence, the wet sacrificial etch is performed prior to defining the gratings. The process is also useful in producing other high aspect ratio structures