الفهرس | Only 14 pages are availabe for public view |
Abstract Porous Si nanoparticles offer a number of properties of interest for many applications in different fields of sciences. Nano-porous silicon material is promising platform for many applications because of low toxicity. The pores can be generated anywhere from a few nanometers to several hundreds of nanometers in diameter. The surface of freshly prepared porous Si is easily modified via convenient chemistry with a large range of host specific organic molecules (dyes, surfactants, polymers, etc.), allowing the fabrication of many types of sensors. The optical properties of porous Si provide a useful dimension for in gas sensing and PH-sensing. This thesis consists of three chapters. The first chapter devoted to explore porous silicon material, the difference between silicon and porous silicon, properties of nano Porous Silicon (nPS), classification of nPS, how it forms, several etching mechanisms, Alkali anisotropic etching mechanism and different applications of PS. The second chapter includes several techniques of nPS preparation, thorough explanation of the method actually used in addition to a full review of all the conditions for the preparing process. In addition to, explanation of PHsensor configuration full steps is described. The third chapter shows of all the results of the measurements and accurate analysis used in the chemical process for preparing porous silicon. Examination of PH-sensor working and listing the data results during exposure to different acidic or basic media is discussed. 5 In the present work, wet alkaline chemical etching technique has been used to prepare nPS. Many factors have been studied to obtain the best conditions for the production of nPS. The main factors which affect the production of PS from crystalline silicon as a result of anisotropic etching are the concentration of etching solution (KOH) and the wetting agent (n-propanol), as well as temperature and time of the etching process. Transformation of crystallographic plane of n-Si (2 1 1) to n-PS (1 0 0) is produced by using {(2 wt %) KOH, (15 vol %) n-propanol} at etching .temperature 80 C and etching time 5. |