Fabrication and charactionzation of ZnO porous Si photoconductive UV detector

Other Title(s)

تصنيع و دراسة خصائص كاشف التوصيل الضوئي أوكسيد الخارصين-السليكون المسامي للأشعة فوق البنفسجية

Dissertant

Thjil, Hanan Abd Ali

Thesis advisor

Natiq, Naji Usamah
Suhayl, Abd Allah Muhsin

Comitee Members

Alias, Maysun F.
Muhammad, Ghusson H.
Ismail, Rad A.

University

University of Baghdad

Faculty

College of Science

Department

Department of Physics

University Country

Iraq

Degree

Master

Degree Date

2011

English Abstract

In this work the UV solar blind ZnO photoconductive detector is fabricated.

The Zinc oxid thin films are prepared by thermal chemical spray pyrolysis technique and deposited on glass and porous silicon substrate .

The porous silicon is prepared by photochemical etching process at different etching time (30,60 ,90min).

The structural , morphological, optical properties and electrical properties of the prepared ZnO samples are studied .

The structure of the films are examined by X-ray diffraction (XRD) and found to be polycrystalline of hexagonal structure with strong crystalline orientation at (002).The optical energy gap is calculated by two techniques like the absorption spectrum which gives a value of 3.22eV,3.46eV whereas Eg value from the photoluminescence PL spectrum is found to be 3.46Ev,3eV.The surface morphology studies demonstrate that ZnO nanofilm deposited on PS is improved with respect to the film deposited on glass substrate .The Hall measurements show that the ZnO film deposited on glass substrate is n-type semiconductor, whereas the film deposited on nanospikes silicon layer shows intrinsic .

The I-V characteristics , photoresponsivity , photocurrent gain and the normalized detectivity of the fabricated detector are measured.

The performance of the fabricated detectors are taken under illumination of the ZnO detector film using light power 2.5mW and 385nm UV radiation from GaN UV-led.

The surface functionalization of the ZnO film deposited on porous silicon (PS) layer by polyamide nylon polymer has highly improved the photoresponsivity of the detector to 0.8 A/W.

The response time of fabricated detector was measured by illuminating the sample with Nitrogen laser of 0.3ns pulse duration and 50μJ pulse energy lasing at 337.1nm wavelength and it can be observed a drastically reduced the response time of the ZnO UV detector from few seconds to few hundreds of microseconds .

The normalized detectivity (D*) of the fabricated ZnO UV detector at wavelength of 385 nm is found to be 1.06 ´ 1011 cm Hz1/2 W-1.

List of Symbols and Abbreviations Symbol Description a Lattice constant aB Bohr radius( nm) Abs Absorbance atm Atmosphere A Area(cm2) AFM Atomic Force Microscope Al2O3 Supphire °C Centigrade Degree (unit for measuring the temperature) c Speed of Light C.B Conduction Band CVD Chemical Vapour Deposition c- Silicon Crystalline Silicon d Confinement Diameter D Detectivity DMM Digitail Multimeter e Electron Charge EC Coulomb Interaction Energy Eg Energy Band Gap( eV) opt

Main Subjects

Physics

No. of Pages

78

Table of Contents

• APA
• MLA
• AMA

Language

English

Data Type

Arab Theses

Record ID

BIM-606208