Quantum-Size Effect from Photoluminescence of Low-Temperature-Oxidized Porous Si

We examined the change in photoluminescence spectra of porous Si after several repetitions of chemical oxidation and reduction. We observed the shift to higher frequencies of the photoluminescence peak as the repetition times increased. We also observed the shift to higher frequencies of the photoluminescence when the porous Si was oxidized using synchrotron radiation (SR) followed by chemical reduction. Raman measurements were used to estimate the microcrystalline size of the porous Si. These Raman results indicate that the photoluminescence peak shifts to higher frequencies are closely related to quantum-size effect.