Orientador: José Roberto Ribeiro Bortoleto / Banca: Tersio Guilherme de Souza Cruz / Banca: Marcio Peron Franco de Godoy / Banca: José Humberto Dias da Silva / Banca: Steven Frederick Durrant / Neste trabalho foi realizado o estudo sobre o efeito da pressão e a evolução da espessura nos filmes de AZO, produzidos com alvo metálico e alvo cerâmico através da técnica RF magnetron sputtering. Este estudo teve a finalidade de investigar as propriedades ópticas, estruturais, morfológicas e principalmente as propriedades elétricas, especificamente a causa que leva a baixa ativação dos átomos de alumínio nos filmes de AZO. O mesmo tem despertado a atenção de diversos pesquisadores, a fim de compreender a baixa eficiência de ionização. Para tanto, os filmes de AZO foram submetidos a investigação da pressão de sputtering na faixa de 0,1 a 6,7 Pa, utilizando alvo metálico de Zn-Al (5% at) crescidos a temperatura ambiente. Verificou-se que a melhor pressão de crescimento se encontra em 0,1 Pa, para esta pressão os valores de resistividade e mobilidade apresentada são 8,5x10-4 Ωcm e 17 cm2/Vs e eficiência de ionização 6,2%. Após encontrado o melhor valor de pressão dentro do intervalo estipulado, a evolução da espessura foi investigada apresentando variação de 29 a 1033 nm utilizando alvo cerâmico de ZnO:Al2O3 (3,2% at) a temperatura ambiente. Este estudo revelou que os melhores filmes apresentaram valor médio da espessura entre 130 a 557 nm, com um valor máximo de mobilidade eletrônica de 33,5 cm2/Vs e eficiência de ionização de 18,3%. / In this work the effect of the pressure and the thickness evolution on the AZO films produced with metallic target and ceramic target through the magnetron sputtering RF technique was carried out. This study aimed to investigate the optical, structural, morphological and especially electrical properties, specifically the cause that leads to the low activation of aluminum atoms in AZO films. The same has attracted the attention of several researchers in order to understand the low ionization efficiency. To do so, the AZO films were subjected to sputtering pressure investigations in the range of 0.1 to 6.7 Pa, using Zn-Al metal target (5% at) grown at room temperature. It has been found that the best growth pressure is at 0.1 Pa, for this pressure the values of resistivity and mobility presented are 8.5x10-4 Ωcm and 17 cm2/Vs and ionization efficiency 6.2%. After the best pressure value was found within the stipulated range, the thickness evolution was investigated, varying from 29 to 1033 nm using a ZnO:Al2O3 ceramic target (3.2% at) at room temperature. This study showed that the best films had a mean value of thickness between 130 and 557 nm, with a maximum electronic mobility of 33.5 cm2/Vs and ionization efficiency of 18.3% / Doutor

by Hui Koon-chung = 由電子束照射引起氧化金屬膜覆蓋的氧化鋅之光學特性 / 許冠中. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 87-89). / Text in English; abstracts in English and Chinese. / by Hui Koon-chung = You dian zi shu zhao she yin qi yang hua jin shu mo fu gai de yang hua xin zhi guang xue te xing / Xu Guanzhong. / ABSTRACT --- p.i / ACKNOWLEDGMENTS --- p.iii / TABLE OF CONTENTS --- p.iv / LIST OF FIGURES --- p.vi / LIST OF TABLES --- p.x / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Motivation --- p.1 / Chapter 1.2 --- Overview of ZnO / Chapter 1.3 --- Overview of the Thesis / Chapter 2. --- Experimental conditions and procedures --- p.11 / Chapter 2.1 --- Samples preparation / Chapter 2.2 --- Optical and electrical Characterizations of ZnO / Chapter 2.2.1 --- Setup of cathodoluminescence (CL) spectroscopy / Chapter 2.2.2 --- Setup of photoluminescence (PL) spectroscopy / Chapter 2.2.3 --- Setup of photoconductivity measurement / Chapter 2.2.4 --- Setup of atomic force microscopy AFM / Chapter 2.2.5 --- X-ray photoelectron spectroscopy (XPS) / Chapter 3. --- Experimental results and data analysis --- p.21 / Chapter 3.1 --- The luminescence of ZnO --- p.21 / Chapter 3.2 --- Effects of metal capped layer in luminescence --- p.24 / Chapter 3.3 --- Optical memory effect of A1 capped ZnO --- p.28 / Chapter 3.4 --- The XPS study ofAl capped ZnO --- p.33 / Chapter 3.5 --- Optical properties and photoconductivity studies of AlOx-capped ZnO --- p.35 / Chapter 3.6 --- Time- and Electron-dose dependent CL of AlOx capped ZnO --- p.41 / Chapter 3.7 --- Dependence of band-edge enhancement on Deep Level to band-edge emission ratio --- p.53 / Chapter 3.8 --- Temperature-dependent CL of AlOx capped ZnO --- p.56 / Chapter 3.9 --- Electrical measurement of luminescence enhanced ZnO --- p.64 / Chapter 4. --- Discussion --- p.69 / Chapter 4.1 --- General discussion --- p.69 / Chapter 4.2 --- The effect of AlOx capping on the optical properties of ZnO --- p.70 / Chapter 4.3 --- The action of e-beam irradiation on the enhancement of band-edge emission --- p.73 / Chapter 4.4 --- The function of AlOx layer when under electron irradiation --- p.83 / Chapter 5. --- Conclusions --- p.85 / Reference --- p.87

Wang, Ranshi = 透明电解质/氧化锌异质结热稳定性的研究 / 王然石. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 130-134). / Abstracts in English and Chinese. / Wang, Ranshi = Tou ming dian jie zhi/yang hua xin yi zhi jie re wen ding xing de yan jiu / Wang Ranshi. / Chapter I. --- Abstract / Chapter II. --- Acknowledgement / Chapter III. --- Table of contents / Chapter IV. --- List of figures / Chapter V. --- List of tables / Chapter 1 --- Introduction / Chapter 1.1 --- Motivations / Chapter 1.2 --- Outline of thesis / Chapter 2 --- Experimental Conditions and Techniques Used / Chapter 2.1 --- Sample preparation / Chapter 2.1.1 --- Radio frequency magnetic sputtering / Chapter 2.1.2 --- ITO glass / Chapter 2.1.3 --- Thermal evaporation / Chapter 2.1.4 --- Thermal annealing / Chapter 2.2 --- Optical characterization of ZnO / Chapter 2.2.1 --- Photoluminescence (PL) measurement / Chapter 2.2.2 --- SEM and cathodoluminescence spectroscopy / Chapter 2.3 --- Time-of-FIight Secondary Ion Mass Spectroscopy (TOF-SIMS ) / Chapter 2.4 --- Electrical measurements / Chapter 3 --- Calibrations / Chapter 3.1 --- Sample Thickness / Chapter 3.2 --- Calibrations of cathodeluminescence measurements / Chapter 3.2.1 --- Probe current and specimen current / Chapter 3.2.2 --- Sample uniformity in CL measurement / Chapter 3.2.3 --- Mirror position / Chapter 3.2.4 --- Non-linear relation between CL emission and current / Chapter 3.2.5 --- CL band-edge emission stability / Chapter 3.2.6 --- Effect of magnification / Chapter 3.2.7 --- Effect of electron beam shift / Chapter 3.2.8 --- Conclusions / Chapter 3.3 --- C-V measurement / Chapter 4 --- Experimental Results and Data Analysis / Chapter 4.1 --- Optical properties / Chapter 4.1.1 --- Luminescence of ZnO / Chapter 4.1.2 --- Light emitting thermal stability of A10x (MgO) capped ZnO film / Chapter 4.1.2.1 --- Emission degradations in annealing treatment by PL / Chapter 4.1.2.2 --- Evidence about the interface degradation / Chapter 4.1.2.3 --- CL studies of the emission from sample surface / Chapter 4.2 --- Secondary Ion Mass Spectroscopy (SIMS) studies of AIOx-capped ZnO / Chapter 4.2.1 --- Data processing / Chapter 4.2.2 --- Diffusion width / Chapter 4.3 --- Simulation of Zn out diffusion to the dielectric layer / Chapter 4.3.1 --- Structure and assumptions / Chapter 4.3.2 --- Calculations of diffusion by Fick's Law / Chapter 4.3.3 --- Simulation of PL reduction from diffusion / Chapter 4.3.4 --- Short-time PL / Chapter 4.4 --- Simulation of defects generation in emission reduction process / Chapter 4.4.1 --- Some calculations of continuity equation / Chapter 4.4.2 --- First order equation for defect generation / Chapter 4.5 --- Electrical measurements / Chapter 4.5.1 --- Theory of C-V measurement for MOS structure / Chapter 4.5.1.1 --- MOS Structure / Chapter 4.5.1.2 --- Discussions about surface charge and energy level in C-V experiments of MOS / Chapter 4.5.1.3 --- Useful formulations / Chapter 4.5.2 --- Experimental results of C-V and parameter extraction / Chapter 4.5.2.1 --- Effect of series resistance correction / Chapter 4.5.2.2 --- Effect of thermal annealing to C-V curves on dielectric/ZnO/ITO / Chapter 4.5.2.3 --- Doping concentration (ND) / Chapter 4.5.2.4 --- Discussion about the fixed and mobile charge / Chapter 4.5.3 --- Simulation of C-V relation in dielectric/ZnO / Chapter 4.5.4 --- Current-voltage (I-V) measurements / Chapter 4.5.5 --- Conductance-voltage measurements (G-V) and interface trap density / Chapter 4.5.6 --- DLTS measurements for extracting interface trap density / Chapter 5 --- Discussions and Conclusion / Chapter 5.1 --- Mechanism / Chapter 5.2 --- Conclusions / Chapter 5.3 --- Future plan / Chapter 6 --- References

Xia, Daxue. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

A successful cancer treatment is a combination of early diagnosis and efficient use of anticancer drugs. There is a chance of approximately 70 - 90% of cancer patients surviving if the diagnosis is conducted early. That means if a diagnosis system is in place which can detect multiple types of cancer at an early stage, a potential cancer therapy is most likely to succeed. However, at present, the available biomedical sensors are unable to detect and differentiate between cancerous cells or tumours. They are also not able to provide continuous real-time monitoring of a patient. Additionally, oral anticancer drugs given during chemotherapy, at the moment, suffer from low bioavailability. Also, a variety of these drugs is not targeted in nature. That means the drug will potentially affect areas of the body which do not need it. The low bioavailability of the drug will not only increase the chemotherapy sessions but also makes the entire process more aggravating for the cancer patient. Therefore, there is an absolute need to have innovative and efficient anticancer drug delivery mechanisms. Finally, current biomedical sensors are primarily made up of silicon (Si) or hard substrates based materials. Even if the biomedical sensor is of a flexible material, the material is either a fragile film or flexible but not stretchable polymers such as polyimide (PI). By having a biomedical sensor which is moderately flexible or not flexible at all, a continuous on-body biomedical sensing is not possible in an efficient manner. That is because hard substrates based biomedical sensors would be difficult to be placed on a body at all times. Furthermore, the flexible biomedical sensors currently suffer from problems such as the electrode on top cracking and damaging after few uses rendering them unusable. Hence, a new fabrication process needs to be devised to solve the issues mentioned above. In this work, an attempt is made to utilise zinc oxide (ZnO) nanostructures for biomedical sensing, drug delivery and biomimetics. ZnO nanostructures are synthesised by using a low-cost wet chemistry process known as hydrothermal growth. Due to the inherent biocompatibility and unique electrical/ piezoelectric properties of ZnO, they acted as prime candidates for the applications outlined above. A high-throughput process is used to synthesise ZnO nanowires (NWs) on Si, polyimide-onsilicon (PI/Si) and directly on PI and polydimethylsiloxane (PDMS) substrates. The work utilises a variety of characterization tools. ZnO nanostructures' morphology is characterised by using a Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM) and Atomic Force Microscope (AFM). X-ray diffraction (XRD) was used to calculate the crystallite size and the crystalline orientation of the nanostructures. A novel fabrication process is developed to allow direct synthesis and direct patterning of metal electrodes on fully flexible, stretchable and bendable PDMS substrates by using standard photolithography. This novel fabrication process makes the PDMS substrates not expand when exposed to temperatures up to 110 °C. Also; the new fabrication process does not cause the PDMS to swell when exposed to various chemicals such as isopropyl alcohol (IPA) or acetone. The fabrication process has created a new paradigm shift in the field of patterning and producing devices directly on flexible and stretchable substrates. The PDMS substrate is further utilised as a sensitive bovine serum albumin (BSA) protein sensor which is capable of detecting up to femtomolar concentrations in just under 5 min of incubation time. Protein biosensing tests were carried out by measuring the change in resistance at 1V bias voltage. The PDMS based biosensor is tested as a protein sensor because proteins are important biomarkers in cancer diagnosis. Also, protein sensors are immensely useful in the detection of bacteria and viruses thereby allowing further expansion to the technology developed herewith. For the first time, ZnO NWs are used to deliver hydrophobic organic dye, Nile red, in a human body like environment. The Nile red simulates an anticancer drug as they share similar surface chemistry. There is an approximately 80% release of Nile red which shows that ZnO NWs can be used as an efficient anticancer drug delivery system with high bioavailability. For the drug delivery experiments, the dynamic dialysis based release of Nile red (Nr) from the ZnO nanowires is carried out by using UV-Visible (UV-Vis) spectroscopy. Fourier Transform Infrared (FTIR) was used to determine the coordination of Nr across the ZnO nanowires. Finally, a novel synthesis process is used to produce individual ZnO NWs on a single ZnO nanoplate (NP) which are named as ZNWNP nanostructures. ZNWNP nanostructures have high hydrophobicity without the need of any functionalization. The hydrophobicity of the hybrid ZnO nanowires on ZnO nanoplate nanostructures (ZNWNP) is characterised by using contact angle goniometry (CAG). Various contact angle theories have been used to calculate the surface free energy (SFE) of the ZNWNP nanostructures. The high hydrophobicity allows these nanostructures to be used for biomimetic applications such self-cleaning, bioinspired sensors and multimodal biosensing. Additionally, ZNWNP nanostructures can be used in biomedical sensors to create multimodal analysis. The multimodal analysis is immensely useful in cancer detection as at least three or more cancer biomarkers can be used to triangulate the diagnosis. The work presented in the thesis aims to utilise ZnO nanostructures for a variety of biomedical applications. The new fabrication process mentioned above has applications not only in biomedicine but also in the flexible electronics industry. The biomimetic nanostructures combined with the biomedical sensor gives rise to a robust multimodal analysis system which can change the course of the cancer diagnosis. That coupled with the usage of ZnO NWs as an effective anticancer drug delivery system gives an immense promise in advancing cancer therapy as a whole and making the entire treatment process less aggravating and less painful for cancer patients.

Fang, Qianying = 基於掃描探針顯微鏡(SPM)的關於鋁摻雜氧化鋅(ZnO:Al)局域電學性質之研究 / 方倩莹. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 97-100). / Text in English; abstracts in English and Chinese. / Fang, Qianying = Ji yu sao miao tan zhen xian wei jing (SPM) de guan yu lü shan za yang hua xin (ZnO:Al) ju yu dian xue xing zhi zhi yan jiu / Fang Qianying. / Chapter I. --- Abstract / Chapter II. --- Acknowledgement / Chapter III. --- Table of contents / Chapter IV. --- List of figures / Chapter V. --- List of tables / Chapter 1 --- Introduction / Chapter 1.1 --- Motivations / Chapter 1.2 --- Outline of thesis / Chapter 2 --- Experimental Conditions and Techniques Used / Chapter 2.1 --- Sample preparation / Chapter 2.1.1 --- Radio frequency magnetic sputtering / Chapter 2.1.2 --- Substrates / Chapter 2.1.3 --- Thermal evaporation / Chapter 2.1.4 --- Thermal annealing / Chapter 2.2 --- Microscopic electrical measurement / Chapter 2.2.1 --- Conductive atomic force microscope (c-AFM) / Chapter 2.2.2 --- Scanning capacitance microscope (SCM) / Chapter 2.2.3 --- Surface Potential (SP) / Chapter 2.3 --- SEM and cathodoluminescence spectroscopy / Chapter 3 --- Calibrations / Chapter 3.1 --- Calibrations of c-AFM measurements / Chapter 3.1.1 --- Reproducible images / Chapter 3.1.2 --- Further statistical analysis / Chapter 3.1.3 --- Sample thickness effect / Chapter 3.1.4 --- Conclusions / Chapter 3.2 --- Calibrations of cathodeluminescence (CL) measurements / Chapter 3.2.1 --- Effect of removing residual magnetic field / Chapter 3.2.2 --- Effect of Faraday cup moving / Chapter 3.2.3 --- Time effect / Chapter 3.2.4 --- Effect of mirror shift / Chapter 3.2.5 --- Effect of electron beam shift / Chapter 3.2.6 --- Conclusions / Chapter 3.3 --- Calibrations of scanning capacitance microscope (SCM) measurements / Chapter 3.3.1 --- SCM images and morphological dependence of as-deposited AlOx/ZnO thin film / Chapter 3.3.2 --- Comparison between as-deposited and e-beam irradiated AlOx/ZnO thin film / Chapter 3.3.3 --- SCM images and morphological dependence of e-beam irradiated AlOx/ZnO thin film / Chapter 3.3.4 --- Conclusions / Chapter 4 --- Experimental Results and Data Analysis / Chapter 4.1 --- Conductive Atomic Force Microscope (c-AFM) / Chapter 4.1.1 --- Effect of scan rate / Chapter 4.1.2 --- Dual images and morphological dependence / Chapter 4.1.3 --- Statistic microscopic current-voltage (I-V) / Chapter 4.1.4 --- Schottky barrier at Pt-ZnO contact / Chapter 4.1.5 --- C-AFM artifact / Chapter 4.2 --- Scanning Capacitance Microscope (SCM) / Chapter 4.2.1 --- Dual images and morphological dependence / Chapter 4.2.2 --- Statistic microscopic SCM data-voltage (dC/dV-V) / Chapter 4.3 --- Surface Potential (SP) / Chapter 5 --- Discussions and Conclusion / Chapter 5.1 --- Mechanism / Chapter 5.2 --- Conclusions / Chapter 5.3 --- Future plan / Chapter 6 --- References

Lei, Dangyuan = 表面等離子交叉耦合協助氧化鋅發射的理論和實驗研究 / 雷黨願. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 81-85). / Abstracts in English and Chinese. / Lei, Dangyuan = Biao mian deng li zi jiao cha ou he xie zhu yang hua xin fa she de li lun he shi yan yan jiu / Lei Dangyuan. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Motivations --- p.1 / Chapter 1.2 --- Thesis outline --- p.3 / Chapter 2 --- Background and Proposition --- p.7 / Chapter 2.1 --- Surface plasmon mediated emission from semiconductor --- p.7 / Chapter 2.1.1 --- General mechanism --- p.7 / Chapter 2.1.2 --- Formulation of SP coupling --- p.10 / Chapter 2.1.2.1 --- Derivation of dispersion relation --- p.10 / Chapter 2.1.2.2 --- Plasmonic density of states (DOS) --- p.13 / Chapter 2.1.2.3 --- Field distribution in dielectric/metal/dielectric System --- p.13 / Chapter 2.1.2.4 --- Determination of Purcell factor (Fp) --- p.16 / Chapter 2.1.3 --- Emission enhancement from metal-capped ZnO --- p.17 / Chapter 2.2 --- Proposal for making high efficiency top-emitting LED --- p.22 / Chapter 3 --- Experimental Setup and Measurement System --- p.24 / Chapter 3.1 --- Sample preparation --- p.24 / Chapter 3.1.1 --- Radio frequency magnetron sputtering --- p.24 / Chapter 3.1.2 --- Spin-coating --- p.27 / Chapter 3.1.3 --- Rapid thermal annealing --- p.29 / Chapter 3.2 --- Optical characterizations --- p.29 / Chapter 3.2.1 --- Transmittance measurement --- p.29 / Chapter 3.2.2 --- Photoluminescence (PL) measurement --- p.31 / Chapter 3.2.3 --- EDX for composition measurement --- p.32 / Chapter 4 --- Theoretical Simulations and Experimental Results --- p.36 / Chapter 4.1 --- Tunable surface plasmon resonance by using metal alloys --- p.36 / Chapter 4.1.1 --- Dielectric constants calculation --- p.37 / Chapter 4.1.2 --- Dispersion relation of alloy/Si02 --- p.41 / Chapter 4.1.3 --- Plasmonic density of states and Purcell factor of alloy/semiconductor --- p.43 / Chapter 4.1.3.1 --- Air/AlxAg1-x/ZnO system --- p.43 / Chapter 4.1.3.2 --- Air/AlxAul-x/ZnTe --- p.46 / Chapter 4.1.3.3 --- Air/ AgxAul-x/CdSe system --- p.48 / Chapter 4.1.4 --- Experimental results of AlxAgl-x/ZnO --- p.52 / Chapter 4.1.5 --- Discussion and mini-conclusion --- p.56 / Chapter 4.2 --- Enhanced forward emission from metal-insulator-metal/ZnO by coupled surface plasmon --- p.57 / Chapter 4.2.1 --- Plasmon modes in metal-insulator-metal (MIM) --- p.57 / Chapter 4.2.2 --- Transmittance simulation of MIM and MIMIM --- p.63 / Chapter 4.2.3 --- Transmittance measurement of MIM --- p.68 / Chapter 4.2.4 --- Transmittance and photoluminescence of MIM/ZnO. --- p.73 / Chapter 4.2.5 --- Discussion and mini-conclusion --- p.78 / Chapter 5 --- Conclusions --- p.79 / Chapter 6 --- References --- p.81

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the academic requirements for the degree of Doctor of Philosophy. Johannesburg, 2014. / Unable to load abstract.

Thesis ((MSc. (Physics)) -- University of Limpopo, 2018 / The mechano-chemical technique was employed to synthesise the undoped, cobalt and indium single and double doped ZnO nanoparticles powder samples. The x-ray diffraction (XRD), scanning electron microscopy (SEM), raman spectroscopy (RS), ultraviolet-visible spectroscopy (UV-vis), and photoluminescence (PL) spectroscopy were employed to characterise the prepared samples. The XRD and energy dispersive spectroscopy (EDS) results confirmed that the prepared samples were of hexagonal wurzite form. In addition, it was found that the diffraction pattern for In-ZnO nanoparticles display an additional peak which was associated with In3+ dopant. The peak suggest that In3+ ions prefer the interstitial site in the hexagonal ZnO structure. Doping the ZnO nanoparticles with Co and In did not significantly affect the lattice parameters but the average grain sizes of the nanoparticles were found to be reduced. The morphology of the samples revealed by the SEM images appear to be more spherical. The Raman modes obtained from the excitations wavelength of 514.532 nm further indicated that the prepared samples were of hexagonal ZnO structures. The energy band gap of the prepared samples were calculated from the UV-vis data which showed that the doped ZnO nanoparticles had smaller energy band gap compared to the undoped ZnO nanoparticles. The excitation wavelength of 350 nm were used in the PL study where various defects related emissions were observed for the doped and undoped ZnO nanoparticles. The kenosistec station equipment was used to investigate the prepared samples for gas sensing application. Ammonia (NH3), methane (CH4) and hydrogen sulphide (H2S) gases were probed. In all the response curves observed, the undoped and double doped ZnO nanoparticles are being favoured at a temperature range 200 – 350oC. In addition, the double doped ZnO nanoparticles was found to be more sensitive to CH4 at low temperatures and low v concentrations. / National Research Foundation (NRF) and Council for Scientific and Industrial Research (CSIR)

Growing demand and shortages of potable water sources due to industrialization have become a great concern worldwide. Various approaches and solutions have been adopted to provide cleaner and quality water. In a preliminary study, a method of treating wastewater was investigated in which algae were used to remove nutrients (nitrogen and phosphorous) from wastewater and then the algae were harvested for use as a biofuel. The results from this investigation are included in the Appendix B. Employing traditional oxidants, such as hydrogen peroxide, chlorine, and ozone, for treatment of recalcitrant organic compounds have achieved less promising results. However, photocatalysis, an advanced oxidation process (AOP), which is a low-cost and high-efficiency technique, has been widely recognized as a promising approach for water purification and elimination of organic constituents in wastewater. Photocatalysis is the increase in the rate of a chemical reaction by employing a catalyst in the presence of photons. Generally, for a high performance photocatalyst, light of appropriate wavelength is used to activate a catalyst in close contact with contaminants, thereby modifying the rate of the reaction. The presence of these contaminants could pose potential health and environmental concerns, especially in a controlled environment such as on a space station or during long-term manned missions. Thus, the development of energy efficient and "green" technologies to reduce or eliminate organic constituents in wastewater has important potential applications. This research investigated the supported semiconductor photocatalysts (TiO2 and ZnO), particularly ZnO nanorods and nanowires, their synthesis methods, properties and corresponding effectiveness in photocatalysis. The effect of transition metal co-catalysts on the photocatalytic properties of TiO2 was investigated. Although TiO2 is the most extensively studied photocatalyst for water decontamination, ZnO, as presented in this work, could be a substitute because of its lower cost, relative energy bandgap and higher visible light photoactivity. Both photocatalysts were doped and screened for the decomposition of model contaminates, rhodamine B (RhB), phenol and methyl orange, under ultraviolet and/or visible light irradiation. In the photodegradation of RhB, TiO2/Ru 1% showed a superior photocatalytic activity relative to P25-TiO2 under broad-band irradiation, while doped ZnO-Ag resulted in better photodegradation of methyl orange, compared to P25-TiO2, under visible light irradiation. The morphology and estimated chemical composition of photocatalysts were determined by energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM). Brunhauer, Emmett and Teller (BET) analysis was utilized to measure mass-specific surface area(s). A X-ray diffraction (XRD) study was carried out to confirm the identity of photocatalyst phase(s) present. The cause of low photocatalytic activity under an inert atmosphere, the simple effective fabrication technique of doped ZnO nanowires over TiO2 and properties of the photocatalyst are also discussed.