دراسة خصائص السيليكون المسامي للسيليكون من النوع P والنوع N

Study the Properties of Porous Silicon for P- type and N-type Bulk Silicon

Summary

The thesis includes the preparation of nano porous silicon by the photo electro chemical etching scraping process, using alight with luminous power of (100W) for N-type and electro chemical etching for P- type in the same method of preparation for both types and with the resistivity (R=1-10 Ω.cm) by using different concentrations of hydrofluoric acid/Ethanol at a ratio (39-43%) and ethanol (99%) the operation was carried out with a skimming time of (10 min) and a voltage of (10 volts) .

-Porous silicon has been theoretical studied by means of preparation, physical and chemical properties and applications of porous silicon have been studied .

– We also compared the two kinds by examining the shape and compositional features of porous silicon layers using X-ray diffraction XRD, scanning electron microscope SEM, and gravimetric technique. The X-ray diffraction findings revealed that the difference between the two kinds is minor owing to differences in acid interaction .Either the homogenous is in the medium shape due to their effect with porous silicon. As for the scanning electron microscope images, they showed different shapes. If these shapes change with the change of concentrations, it has been found that the width of the pores and the thickness of the porous silicon layer increases as the acid concentration decreases.

– As for the porosity values of the porous silicon layers measured using the gravimetric method for both types, it was found that the porosity changes due to the strength of the reaction concentration, If it increases as the acid concentration decreases due to the occurrence of more polishing, which leads to an increase in density due to the large amount of voids in the porous silicon layer and decreases with increasing the concentration .A weak porous silicon layer is produced which results in a small amount of voids