Abstract
The effects of light illumination on porous silicon (PSi) properties have been studied using photoluminescence (PL), PL excitation (PLE), and x-ray photoelectron spectroscopy (XPS) measurements. The PL spectrum evolution in PSi sample under light illumination at various wavelengths indicates that the photo-oxidation occurs and causes a decrease in its intensity with increasing illumination time t. The decrease in the PL intensity IPL can be written as logarithmic expression, namely, the Elovich equation IPL∝−α ln t, where α is the quenching rate of the PL intensity associated with the native oxide growth. The α value is dependent on the illuminated photon energy Epo in a manner α=0.050Epo. Each PL spectrum can be deconvoluted into four Gaussian peaks. The higher the PL peak energy, the larger its photo-oxidation-induced blueshift. This fact and XPS results support that the light emission in a porous sample is due to the quantum-size effect, i.e., relaxation of the momentum conservation at and above the indirect absorption edge (supra-indirect-gap emission). The PLE spectra suggest that the surface hydrogen termination should influence the highly excited carrier dynamics in nanocrystalline PSi materials.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
