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Effect of Transition Metals Doping on the Properties of Zno Thin Films

Thesis Info

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Author

Nawaz, Muhammad Asif

Program

PhD

Institute

The Islamia University of Bahawalpur

City

Bahawalpur

Province

Punjab

Country

Pakistan

Thesis Completing Year

2016

Thesis Completion Status

Completed

Subject

Physics

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/13376/1/Thesis%20by%20Muhammad%20Asif%20Nawaz%2c%20PhD%20Physics%2c%202016.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676726003999

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Nanotechnology is a technology of resizing and the applications of nanosized materials. Zinc oxide (ZnO) nanostructures became a potential candidate in various applications due to their direct wide bandgap, high exciton binding energy, good chemical stability, radiation hardness, notable optoelectrical, pyroelectric and piezoelectric properties. By doping with different metals (T = Co, Mg, Sr, Sb and P) into ZnO matrix, various properties of ZnO nanostructure could be tuned. The aim of this dissertation was to develop a simple approach to synthesis as-grown and T-doped ZnO by using hydrothermal technique because of its low cost, simple solution process, environment friendly and easy to handle. The grown samples were characterized to study the enhancement in different functional properties for applied applications. The first part of dissertation deals with synthesis of as-grown ZnO nanostructure via hydrothermal method. Microstructural and morphological properties of as-grown and annealed ZnO can be calculated by X-ray diffraction (XRD), Williamson-Hall (W-H) analysis via three different models of uniform deformation model (UDM), uniform deformation stress model (UDSM) and uniform deformation energy density model (UDEDM) and transmission electron microscopy (TEM) respectively. These models were used to calculate other physical parameters such as stress, strain and energy density values. The results showed that the estimated value of crystallite size (D) from W-H analysis by using UDM is highly inter-correlated with the particle size estimated from TEM and do not show much deviation. The second part of the dissertation demonstrates hydrothermal synthesis of T-doped ZnO and study the effect of T dopant levels on the morphological, microstructural, dielectric, magnetic and optical properties of ZnO nanostructure. Dielectric constant of cobalt (Co) doped ZnO samples have been found to be decreased by increasing the dopant levels. Loss tangent results of doped samples reveals the decrease in hopping frequency of charge carriers between metals ions with dopant ion. Considerable increases of optical bandgap while maintaining good hexagonal structure with no other impurity by increasing the Co dopant concentration have been observed. The antimony (Sb) doping shows stronger effect on the length of nanowires (NWs) which is ~ 11 times longer and slight red-shift is observed in photoluminescence (PL) peak as compared to as-grown ZnO. It is argued that the observed red-shift and broadening in PL response are associated with Sb-doping level and/or from Sb defect states partially. For strontium (Sr) doped ZnO films, the surface morphological, microstructural properties, optical binding energy and band-to-band emission have been examined. It is observed that the crystalline quality improved by increasing the Sr dopant level while optical bandgap and band-to-band emission is decreased due to lattice distortion and generation of active defects in ZnO crystal; it may cause bandgap tailing. Magnesium (Mg) doped ZnO nanorods (NR‘s) samples were annealed at 450 ºC, 550 ºC and 650 ºC under the argon (Ar) environment. The XRD spectrum shows that the Mg-doped ZnO NR‘s are crystalline in nature and wurtzite hexagonal phase. The particle size of 550 ºC and 650 ºC Mg-doped ZnO NR‘s estimated from TEM is ~ 126 and 154 nm respectively. We have studied the progression of crystallite size (D) through the use of X-ray peak profile analysis (XPPA). Scherrer formula and three different models of W-H analysis are used which show the increase in grain size and decrease in microstrain by increasing the annealing temperature of Mg-doped ZnO NR‘s. Phosphorus (P) doped ZnO samples have been sintered in air in the range 500-1000 ºC with a step of 100 ºC for one hour in a programmable diffusion furnace. It is observed that forward shift in 2 theta value of the XRD pattern of ZnO sintered at 1000 ºC occurs. This forward shift may correlate with the involvement of P ions with vacancy at Zn-site. Theoretical calculations on a 32-atom super cell of P-doped ZnO further supported the argument and suggests the phosphorous dopant are shallow acceptor PZn-2VZn complex on Zn-site. Typical PL spectra displayed band-to-band emission peak and an additional donor-acceptor peak at ~ 3.14 eV in all P-doped samples.
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غضنفر عباس سیّد کی یاد میں

غضنفر عباس سیّد کی یاد میں

’’زیرِ آب چراغ‘‘ کے خالق
جانے آپ کو کیا جلدی تھی
ابھی تو میں کالج آیا تھاا؎
آپ بھی ہوتے ہمیں میّسر
ہم سب مل کر بیٹھا کرتے

۱؎ 2018ء میں پنجاب پبلک سروس کمیشن کے ذریعے منتخب ہونے کے بعدشعبہ اردو گورنمنٹ کالج ساہیوال میں بطور لیکچرر تقرری ہوئی۔

علمی ادبی باتیں کرتے
چائے کے دور بھی چلتے رہتے
غزل کے پھول بھی کھلتے رہتے

’’زیرِ آپ چراغ‘‘ کے خالق
جانے آپ کو کیا جلدی تھی
آپ تو شعبے کی رونق تھے

جب میں شعبہ آیا کرتا
آپ کو بیٹھے دیکھا کرتا
دیکھ کے اب وہ خالی کرسی
دل یہ میرا کٹ جاتا ہے
اندر میرا پھٹ جاتا ہے

’’زیرِ آب چراغ‘‘ کے خالق
جانے آپ کو کیا جلدی تھی

النزعة الصوفية في شعر خوشحال خان

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Atomic Hyperentanglement: Generation and Applications

Quantum mechanics is entirely counterintuitive and exhibits a multitude of mysterious traits. In this entanglement is one of the earliest and most debated mystery highlighting nonlocality and anti-realism at its zenith. This phenomenon at one side helped to clear philosophical foundations of the theory whereas at the other end, the same phenomenon is being exploited for protocols of quantum information processing (QIP) and quantum communication. Most of these earlier entanglement generation and applications research employed the single qubit while minimizing physical resources as well as the systems with long decoherence times. Exploration of hyperentangled state is one of the milestones towards this quantum revolution because hyperentangled states tremendously boost quantum information and communication capacity due to their high information content per quantum entity. Till now, mostly the engineering and manipulation of such states were, however, limited to the photonic systems only. In the present thesis, we propose the schemes for atomic hyperentanglement generation and applications through applying state of the art tool of Atomic Bragg Diffraction (ABD). We present entangled states consisting of atomic internal energy levels as well as atomic external momenta states for generation of atomic hypersuperposition, hyperentangled cluster-, Bell- and GHZ-states engineered deterministically through resonant and off-resonant Bragg diffraction of neutral twolevel atoms in conjunction with semi-classical atom-field interaction along classical momenta axes. Further we propose Remote State Preparation through these atomic hyperentangled states and prepare upto N-atoms state remotely. Our RSP scheme certainly offers high capacity quantum communication with good fidelity as these atomic hyperentangled states have minimum risk of decoherence and provide evident benefits of full controllability along with extremely high detection efficiency over the counterpart photonic states. We have also employed an atomic hypersuperposition state, duly pre- and post-selected, to investigate Quantum Cheshire Cat (QCC) paradox and proposed an Atomic Cheshire Cat (ACC) that strangely enough exhibit energy signature of atom in that arm of ABD interferometer where no atom is detected in momentum space. Finally thesis concludes with a general discussion as well as marking the feasibility of presented proposals for applications in quantum communications and in explorations related to foundational issues of quantum mechanics.