A photoelectrochemical process has been developed that is capable of producing surface relief holograms on semiconductor crystals. The exposure characteristics of this recording process have been measured, and an analysis of their effect on the reconstructed image is presented. The photoanodic engraving (PAE) process applied to silicon wafers has produced holographic storage densities exceeding 105 bits/ cm2 for data mask type objects. These surface relief holograms have an archival permanence unequaled by any other holographic recording medium. Replication of the surface relief holograms on clear vinyl plastic has been achieved with storage densities of approximately 5 × 103 bits/cm2.
A. L. Dalisa and D. J. DeBitetto, "Data Storage, Retrieval, and Replication Using Photoanodically Engraved Holograms," Appl. Opt. 11, 2007-2015 (1972)