PHOTODISSOLUTION AND PHOTOLUMINESCENCE QUENCHING OF POROUS SILICON INHF

A photodissolution process occurs when porous silicon samples, immerse d in HF solutions, are continuously illuminated. In situ reflectivity measurements allow us to deduce the time evolution of: the optical ind ex: the thickness of the porous layer: and the number of atoms dissolv ed per unit time, which is found to be proportional to the specific su rface of the sample exposed to HF. We have also compared photoluminesc ence properties of porous samples dried and immersed in HF under conti nuous and pulsed UV excitations. Photoluminescence can be totally or p artially quenched and lifetimes are at least two orders lowered in HF solutions. The relevant parameter of the quenching is again the specif ic surface of porous silicon in contact with the liquid, suggesting th at photoluminescence quenching and photodissolution have the same orig in. (C) 1996 American Institute of Physics.