Photoluminescent studies on porous silicon/tin oxide heterostructures

Porous silicon (PSi) structure was formed at different current densities in the range of 5–60 mA/cm2 by the electrochemical anodization of PSi wafers etching in HF for 30 min. The PSi was characterized by X-ray diffraction studies. The PSi samples prepared at current densities above and below 30 mA/cm2 show PL spectra with asymmetric and overlapped peaks. On the top surface as well as inside the pores of this PSi structures the precursor sol–gel was incorporated by the spin coating technique and SnO2 was formed by heating at 400 °C in air. Peaks pertaining to PSi along with those corresponding to SnO2 were observed, which confirmed SnO2 formation as thin film on the PSi surface. The PL spectra of SnO2/PSi structure aged for two months indicated a reduction in PL intensity but remained constant afterwards. SnO2 not only modifies the nature of silicon nanopores but also is expected to influence the interface states in SnO2/PSi junction.

Research highlights▶ P-type silicon electrochemically etched at different current densities. ▶ SnO2 films deposited on porous silicon by spin coating. ▶ SnO2 modifies silicon nano pores and interface states. ▶ PL intensity decreased and remained constant beyond two months.