Environmental effects on stored porous silicon producted by laser assisted etching

مقدم أطروحة جامعية

Ali, Wail Hassan

مشرف أطروحة جامعية

Ulwan, Ulwan M.

الجامعة

الجامعة التكنولوجية

الكلية

-

القسم الأكاديمي

قسم العلوم التطبيقية

دولة الجامعة

العراق

الدرجة العلمية

ماجستير

تاريخ الدرجة العلمية

2011

الملخص الإنجليزي

-In this research; nanostructures porous silicon (PS) layer was fabricated by laser assisted etching process (LAE) using 655nm laser diode at different illumination intensities 10mW/cm2, 40mW/cm2, 100mW/cm2and 200mW/cm2of n-type silicon substrate of resistivity (1.5-4.5Ω.cm) in HF of 24.5% .

The process is carried out at a fixed etching current density of 20mA/cm2and two etching times 10min and 20 min .

The storage media (ambient air and methanol ) effects on the general characteristics of the prepared samples were studied for different aging periods 2,4,6,8 and 16 weeks at room temperature .

Morphological, photoluminescence and electrical characteristics show dramatic changes after aging process .

The aging of (PS) in methanol did not produce significant changes in the morphological and photoluminescence properties of (PS),while the aging process of high porosities (PS) layer in ambient air lead to improve the photoluminescence intensity with a blue shifting in (PL) peak position.

The low porosities (PS) layer under the same conditions also exhibits a blue shift in the central peak wavelength when increasing aging time but the photoluminescence intensities tend to decrease .

The pores sizes, sizes distributions, and specific surface area decrease with increasing aging times in ambient air due to the growth of oxide layer within the (PS) structures .

The electrical properties of (PS) samples show two different behaviors: first a very high resistivity porous silicon layer without rectification behavior (linear characteristic )in fresh samples, and second strong rectification behavior in (stored samples) with different rectification ratio.

التخصصات الرئيسية

الفيزياء

الموضوعات

• الخواص الكهربائية
• الخواص الضوئية
• السيليكون

• APA
• MLA
• AMA

لغة النص

الإنجليزية

نوع البيانات

رسائل جامعية

رقم السجل

BIM-305286