Ag-doped Sno2 sensor for H2S gas, prepared by PLD

مقدم أطروحة جامعية

Shakir, Suad Salim

مشرف أطروحة جامعية

Haydar, Adawiya Jumah

الجامعة

الجامعة التكنولوجية

الكلية

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القسم الأكاديمي

قسم العلوم التطبيقية

دولة الجامعة

العراق

الدرجة العلمية

ماجستير

تاريخ الدرجة العلمية

2013

الملخص الإنجليزي

Tin dioxide (SnO2) has been extensively studied and demonstrated to be suitable to detect toxic gases such as H2S, which affects the quality of life.

Therefore; SnO2 thin films are good candidates in the gas sensor applications .Additionally noble metal dopants to the Tin dioxide materials have improved their sensitivity to H2S gas.

In this work, a Nd:YAG laser beam, λ=532nm, repetition rate 1 Hz with the pulse duration 10 ns and laser fluence 1.2 J/cm2, has been used to deposit pure SnO2 and doped with Ag at various doping percentages 1 wt.%, 2 wt.% and 3 wt.% on glass and silicon substrates.

Basic material characterizations have been studied for these films to specify the optimum conditions namely; a substrate temperature in the range 200-500ᵒC and oxygen pressure of 10-2 -5×10-1 mbar.

SnO2 pure and doped with noble metal were investigated by using different techniques such as X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), Atomic Force Microscope (AFM), UV-VIS transmittance Spectroscopy, Hall Effect, and sensing properties equipment.

As a result, it has been found that film structure and properties are dependent on substrate temperatures and doping concentration.

X-Ray Diffraction (XRD) results showed that at a substrate temperature higher than 200ᵒC, the structure of the deposited thin films changed from amorphous to crystalline case.

SEM and AFM results showed the surface morphology of the deposited materials and the grain size of the nanoparticles observed at optimum condition of 400°C and partial pressure of oxygen 5×10-1 mbar.

The Root Mean Square (RMS) roughness of (11.3nm) was increased with the increasing of substrate temperature (Ts) for thin films deposited at 400ᵒC and for SnO2 thin films doped with 3% Ag concentration and the sample was very rough with RMS value of (30.1 nm ).

UV-VIS transmittance measurements illustrated the films were highly transparent in the visible region; with high transmittance of (78%-94%) for all films.

Dopants with Ag shifted the absorption edge of SnO2 towards the visible region.

Hall Effect was studied to estimate the type of carriers.

From the results it was deduced that the pure SnO2 and the doped films were n-type.

The sensitivity of SnO2: 3%Ag to H2S gas with concentration 3ppm at room temperature has been modified to (84 - 94) % as compared with a pure SnO2.

التخصصات الرئيسية

العلوم الهندسية والتكنولوجية (متداخلة التخصصات)

• APA
• MLA
• AMA

لغة النص

الإنجليزية

نوع البيانات

رسائل جامعية

رقم السجل

BIM-418440