Role of surface texturization on the gas-sensing properties of nanostructured porous silicon films

In this work, by means of high-resolution X-ray diffraction, excitation λ-dependent photoluminescence (PL) and Fourier transform infrared studies, it has been demonstrated that hydrogen-passivated porous silicon (PS) films with high PL and stability can be obtained on p-type Si(1 0 0) substrate by simple texturization process rather than by resorting to any anodic, chemical or thermal oxidation of PS [T. Karacali, B. Cakmak, H. Efeoglu, Opt. Express 11 (2003) 1237]. PS formed on textured substrates is superior to PS formed on polished silicon substrates at the same current density and time of anodization. The application of PS films formed on textured substrate as a gas sensor has been demonstrated and it shows higher sensitivity values upon exposure to ethanol as compared with polished PS specimens of similar porosity. The improved properties are attributed to the formation of highly porous vertical layers separating macroscopic domains of nanoporous silicon.