Fabrication and characteristics study of ZnO Si heterojunction by DC magnetron sputtering

مقدم أطروحة جامعية

Jarrah, Radiyah Mahdi Shakir

مشرف أطروحة جامعية

Ilyas, Maysun Faysal Ahmad
al-Lami, Husayn Khazal Rashid

أعضاء اللجنة

Yasir, Mahdiyah A.
Naji, Iqbal Siham
al-Rasul, Khalid Taha
Ismail, Raid A.

الجامعة

جامعة بغداد

الكلية

كلية العلوم

القسم الأكاديمي

قسم الفيزياء

دولة الجامعة

العراق

الدرجة العلمية

دكتوراه

تاريخ الدرجة العلمية

2013

الملخص الإنجليزي

In this work, ZnO was sputtered using d.c magnetron sputtering which was performed with Zn target and oxygen plasma.

The films deposited on glass substrate and Si wafer under different deposition conditions and annealed at various annealing temperatures were employed to assess film properties and applications as optoelectronic devise (detector and solar cell).

X-ray diffraction studies show that the structure of all ZnO films is polycrystalline with hexagonal wurtizte structure with preferential orientation in the (002) direction.

The effect of the oxygen flow from 20 to 50 sccm on the structural, electrical, and optical properties of the ZnO thin films were studied.

It was found that flow rate leads to higher growth rate, better crystallinity, lower electron carrier concentration, larger resistivity and increasing the band gap energy.

The d.c resistivity of the films prepared under different conditions was measured and was found to be in the range of (103-10-1) Ω.cm.

Hall measurements showed that all the films are n-type .From a.c measurements and according to the behavior of both conductivity and exponent (s) one can suggested the correlated barrier hopping (CBH) model.

The optical measurement showed that the nature of the optical transition has been direct allowed with average band gap energies varies in the range of (3.2 -3.5) eV with change deposition parameter.

The extent and nature of transmittance and optimized band gap of the material assure to utilize it for photovoltaic applications.

ZnO/Si heterojunction has been prepared.

The reverse bias capacitance was measured as a function of bias voltage at frequency 10 kHz, and it is indicated that these heterojunctions are abrupt.

The built in potential (Vbi) as well as the width of depletion layer (W) increases with increasing of thickness, annealing temperature, and also with oxygen flow rate The current–voltage characteristic of ZnO/Si heterojunction show that the forward current at dark varies with applied voltage and the heterojunction was coinciding with recombination-tunneling model.

The dark current initially increases with thickness until 150 nm then it decreases with increase of the thickness.

We also observed that the dark current increases with increase of Ta.

Under illumination, the photocurrent increases with increase of Ta and with thickness until 150 nm then it became decreases.

The Isc and Voc have been studied, and show a decrease with increasing thicknesses from 150 to 250 nm, while it increases with increase of Ta.

The best value obtained at thickness = 150 nm.

The spectral response of ZnO/Si detector was studied.

The maximum value of responsivity occurred at wavelength between 360 nm and 400 nm.

The values of specific detectivity (D*) and quantum efficiency (η) decrease and shift to higher wavelength with increase of thickness.

Their maximum value where at thickness equal to 150 nm, while increase and shift to shorter wavelength with increase of the oxygen flow and Ta, It has been observed that the best spectral response occurs when the oxygen flow equal to 50 sccm and thickness equal to 150 nm, so we can say that this value of oxygen flow and thickness is the optimum condition for prepared ZnO photovoltaic detector.

Doped ZnO with Al and Sb deposited on n- and p-Si were fabricated and the figure of merits of these heterojunections were investigated.

Chances to achieve ptype doping can be improved by designing growth conditions that destabilize the formation of compensating centers, which is important for optical device applications.

التخصصات الرئيسية

الفيزياء

عدد الصفحات

148

قائمة المحتويات

• APA
• MLA
• AMA

لغة النص

الإنجليزية

نوع البيانات

رسائل جامعية

رقم السجل

BIM-607869