الفهرس 
AbstractOnly 14 pages are availabe for public view
 |  | from | 16 |  |  |
| | | from | 16 | | |
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.