Non linear effects of nanostructures silicon

Dissertant

Muhammad, Muhammad Salman

Thesis advisor

Rashid, Bassam Ghalib

University

University of Technology

Faculty

-

Department

Computer Sciences Department

University Country

Iraq

Degree

Ph.D.

Degree Date

2010

English Abstract

Silicon Nanos-tinctures have been synthesized by electrochemical, photocell Petrochemical and laser-induced etching techniques.

Various porous layers constituting; silicon nanostructures of different features were prepared due to silicon atoms detachment by the etching process.

We have extensively investigated the preparation dynamic of the n a no structured silicon during the etching process for the above-mentioned techniques.

This investigations based on the non-linear phenomenon which is called self-phase modulation.

In-situ monitoring, of the preparation dynamic could provide a valuable information about the progress of the nanostructured layer formation which makes the production mechanism real able and controllable.

It is found that the nanostructured layer generates an optical fringe patterns when the nano crystallite size decreases less than (8 mm) due to the quantum confinement effect which enhances the non-linearity of the refractive index of the porous layer.

It is found that the minimum mean nano crystallite size was CI-3 nm) which is obtained at 5 minutes irradiation time, 15 W / cm3 and 532 nm wavelength while optimum change in the refractive index was (0.49) at 7 minutes, IS WVcm2 and S10 nm wavelength.

Moreover, the maximum change in the reflectivity of the porous layer was (0.43) when laser wavelength of 645 nm, 10 W / cm3 and 5 minutes irradiation time.

Tike surface morphology investigations reveal that the nanostructured layer of various structures could be produced and that depends on the preparation parameters.

Moreover, gratings of sabmicjoiis scale can be made when proper processing parameters are selected precisely, The SEM statistics imply that high pore density of smaller average pore diameter of 3 Jim are obtained when the HF concentration diluted to 30 % while the number of pores and average pore diameter (pore density) decreases from (45) and (1.5 urn) to (16) and (4, 5 jute) when, the silicon wafer resistivity increases from 0.015 to 4 £2.cnn, respectively.

Main Subjects

Physics

Topics

• Nanotechnology

• APA
• MLA
• AMA

Language

English

Data Type

Arab Theses

Record ID

BIM-304940