Yasmeen Zaidan Dawood
In this work, an ultrasonically enhanced chemical etching, to fabricated porous silicon layer. Porous silicon layer is fabricated in p-type (111) orientation silicon by using HF solution, and HNO3. It was found the structure of PS layer on p-type Si was improved by ultrasonic.Ultrasonically enhanced chemical etching is developed to fabricate luminescent porous silicon (PS) material.By applying ultrasonically enhanced etching, PS microcavities with much higher quality factors can be fabricated. The effect is attributable to effective change in the concentration of free holes carriers. Raman scattering measurement on (111) oriented Pp-type crystalline silicon (c-Si) and PS samples were carried out. Raman scattering from the optical phonon in PS showed the red shift of the phonon frequency, broadening and increased asymmetry model of the Raman mode on increasing the power of US. Using the phonon confinement model, the average diameter of Si nanocrystallinies has been estimated a 9nm and 10nm for 30W and 50W.the relationship between the width, shift and asymmetry of the Raman line is calculated and is in a good agreement with available experimental data.