Researchers at the University of Science and Technology of China in Hefei report strong emission around 435 nm from porous silicon, which could facilitate the integration of silicon LEDs and electronics on one chip. To build the sample, they etched (100)-oriented single-crystal silicon wafers in an aqueous solution, onto which they deposited a thin layer of PZT.

Blue emission was stable and visible to the naked eye after exposure in an ambient atmosphere for one year. They believe the emission results from the recombination of excited carriers from silicon nanocrystallites in the interfacial region of the silicon and PZT.