THERMALLY-INDUCED MODIFICATIONS IN THE POROUS SILICON PROPERTIES

Various porous silicon (PS) properties are significantly modified by thermal annealing. For example, when a freshly prepared sample is annealed al 450 degrees C, there are a significant reduction of the photoluminescence (PL) intensity, a change in the optical constants (refractive index and absorption coefficient), a sharp decrease in the material strain, hydrogen desorption, and change in the microstructure. The modification of all the parameters listed above (strain, PL, absorption coefficient, microstructure etc.) occurred for annealing temperatures between 350 and 450 degrees C, and that is the same temperature range at which hydrogen is desorbed from the PS surface. The relationship between these parameters and the results of this comparison are discussed.