Photoluminescent thin-film porous silicon on sapphire

Abstract

Results from the chemical stain etch fabrication and analysis of thin-film photoluminescent porous silicon on sapphire substrates are presented. The transparent sapphire substrate allows the excitation and collection of the luminescence at either the front or back of the wafer. Morphological differences found using scanning electron microscopy between porous SOS and porous bulk silicon are attributed to preferential etching of threading dislocations. This is confirmed by an observed stress relaxation in the Raman spectra. Also, it is shown for the first time that photoluminescent porous silicon (n-type) can be produced by photoinitiation of the chemical stain etch.