Study of laser effects on porous silicon properties

مقدم أطروحة جامعية

Muhammad, Arina Faraj

الجامعة

الجامعة التكنولوجية

الكلية

-

القسم الأكاديمي

قسم العلوم التطبيقية

دولة الجامعة

العراق

الدرجة العلمية

ماجستير

تاريخ الدرجة العلمية

2006

الملخص الإنجليزي

Porous silicon constituting silicon nanocrystailite is of great interest for the futuristic optoelectronic applications due to its large surface area and intense photoluminescence at room temperature.

The investigation reported here provides some new insights into the porous silicon formation and characterization.

The porous structure has been produced using laser light during the electrochemical etching process.

To examine effects of the laser illumination, other processes such as laser-induced etching and electrochemical etching were carried out in this study.

We have studied some of the optical, electrical and structural properties of the prepared porous samples by these processes.

Various affecting parameters were studied such as the illumination wavelengths, irradiation time, illumination direction, current density, HF concentration...etc., to investigate their effects on the porous surface morphology, etching rate, photoluminescence and electrical properties of the produced porous layer.

It is found that light illumination leads to form two porous layers and this illumination modifies the porous layer characteristics for p-type silicon while it initiates the etching process in n-type silicon.

A theoretical quantum confinement model has been used to fit the experimental photoluminescence spectra in order to estimate the Nano crystallites sizes constituting the porous structure and their distribution.

According to this spectroscopic method, one can control the photoluminescence emission by choosing appropriate preparation conditions to achieve the optimum intensity.

The structural properties of the porous silicon have also been studied.

It is found that the surface morphology of the porous layer is strongly dependant on the laser wavelength, illumination duration and direction.

Moreover, the surface morphology of the porous layer is affected by the etching current density and the substrate conductivity and resistivity.

Various morphologies such as column-like or pore-like and trench-like structures could be obtained.

Furthermore, the surface area measurements reveal that illumination of porous layer during the etching process leads to increase the surface area.

Similarly, the surface area could be increased by employing shorter wavelengths, long irradiation time and backside illumination.

Finally, electrical properties of the porous samples exhibit high resistivity of the porous layer compared with crystalline silicon which could be controlled through many affecting parameters.

This study reveals that the porous silicon prepared by photo electrochemical etching could be used for many interesting applications due to its superior features.

التخصصات الرئيسية

الفيزياء

الموضوعات

• الخواص الكهربائية
• السيليكون
• أشباه الموصلات
• الليزر

• APA
• MLA
• AMA

لغة النص

الإنجليزية

نوع البيانات

رسائل جامعية

رقم السجل

BIM-305762