Polycrystalline p-Cu2O were fabricated by reactive rf magnetron sputtering . we found that The electrical, optical, and crystallographical properties of films were strongly dependent on the deposition condition . Grant size increasing in the range from 10 to 45nm , A hole concentration increasing in the range from 1016 to 1017 cm-3 and a mobility increasing on the order of 10-1 cm2/V s were obtained in the cuprous oxide thin film prepared by controlling work pressure (Argon partial partial pressure ) . Fabricated thin-film heterojunction diodes consisting of a p-type cuprous oxide combined with and n-type Al-doped ZnO and ITO exhibited a rectifying current-voltage characteristic .

Photocatalysis is a growing area of study for a clean and renewable energy source, particularly for the purification of water and air. Researchers have studied the combination of various semiconductors to create photocatalysts with improved activities, but little has been reported in selecting semiconductors based on their extrinsic type – namely n-type or p-type. In this study, a BiOBr (p-type)-Bi2WO6 (n-type) heterojunction semiconductor was synthesized by the facile hydrothermal method. The new materials were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and diffuse-reflection spectroscopy (DRS). Degradation of Rhodamine B was employed to measure the photocatalytic activity of the as-prepared photocatalysts. On the basis of these techniques, the influence of the synthesis conditions (namely, hydrothermal reaction time and temperature) and the degradation conditions (namely, initial concentration, pH of the initial dye water and amount of catalysts dosage) have been explored and discussed. Furthermore, effect of concentrations of the dopants (the atomic ratio of BiOBr and Bi2WO6 were 1:4， 1:1， 4:1) was examined by measuring the degradation rate of Rhodamine B. Finally, the mechanism of the degradation process and the enhancement effect of heterojunction were also interpreted by analyzing the quenching effect of the scavengers and the band structure. Conclusively, this study shed light on the benefits of using heterojunction photocatalysts, and also on the importance of considering the semiconductor type when forming composite photocatalysts.

We analyze a toy model for p-n junction photovoltaic devices by simulating photoexcited state dynamics in silicon nanowires. One nanowire is approximately circular in cross section with a diameter of d = 1.17 nm. The other has an approximately rhombic cross-section with d1 = 1.16 nm and d2 = 1.71 nm. Both nanowires have been doped with aluminum and phosphorus atoms and capped with gold leads. We use Boltzmann transport equation (BE) that includes phonon emission, carrier multiplication (CM), and exciton transfer. BE rates are computed using non-equilibrium finite-temperature many-body perturbation theory (MBPT) based on Density Functional Theory (DFT) simulations, including excitonic effects from Bethe-Salpeter Equation. We compute total charge transfer amount generated from the initial photoexcitation and find an enhancement when CM is included. In particular, we see between 78% and 79% enhancement in the smaller wire, while we see 116% enhancement in the larger nanowire

The discovery that phosphorylation of proteins occurs on nitrogen by particular kinases raises the question of whether a separate class of phosphoramidases also exists, or if known phosphatases carry out the hydrolysis of phosphoramidates. The phosphoramidase activity of a number of phosphatases with different catalytic motifs was studied using the substrates N-phenylphosphoramidate (N-phPAM) and phosphoryl imidazole (PIm). The phosphatases assayed were: the protein tyrosine phosphatase YopH; alkaline phosphatase; the dual-specificity phosphatase VHR; prostatic acid phosphatase, PAcP; PHPT1, the only known phosphohistidine phosphatase; and, the serine/threonine phosphatases Lambda PP and PP1. The catalytic efficiencies, kcat/KM (s-1M-1), were compared for the respective phosphoramidase and phosphatase activities for each enzyme. Ratios of catalytic efficiencies (kcat/KM)/(kcat/KM) of pNPP over PIm are: YopH - 27; AP - 4.1; VHR - 0.22; PAcP - 1.6; AP - 0.51; and PHPT1 - 0.00007. Lambda PP catalyzed hydrolysis of PIm, although kinetic constants could not be obtained. PP1 exhibited no phosphoramidase activity. The results show that most phosphatase catalytic motifs display catalytic promiscuity by cleaving both phosphoesters and phosphoramidates, but with a pronounced preference for one substrate type versus the other.

This thesis investigates the effects of varying the crystallographic orientations of epitaxial ZnO thin films to produce functional ZnO P-N diodes. First, with the atomic layer deposition (ALD), a p-type m-oriented ZnO epitaxial layer is deposited onto an also m-oriented Al2O3 substrate. Then an n-type ZnO layer, mostly textured along the c-axis, is grown atop to form a P-N diode by RF sputtering method. The Hall Effect of the m-ZnO thin film is measured separately at various temperatures and magnetic fields in Quantum Design¡¦s Physical Property Measurement System (PPMS) to determine the nature of the charge carriers. The m-oriented ZnO films are found to be p-type semiconductors, with carrier concentration approximately ~ 1021 1/cm3, which falls in the category of highly-doped degenerate semiconductor. In order to further prove that these films are indeed p-type, naturally n-type c-textured ZnO films are put on the m-films at room temperature by magnetron sputtering to see if the current-voltage (I-V) curves do follow the P-N junction characteristics. In optimizing the c-ZnO film quality and reducing the effects of the junction defects, the gas-mixture ratio between argon and oxygen was varied to compare for the changes in the performance of the resulted materials and devices. X-ray diffraction was used to characterize the crystallographic orientations and the general qualities of the samples by 2£c-£s scan, rocking scan, £p-scan and pole figure measurement. Understanding of the P-N diode is acquired through the analysis of the leakage current and the quantum tunneling phenomena as manifested in the I-V characteristics.

There are many intensive researches for zinc compounds due to their wide band gaps and potential applications in visible and UV optoelectronic technologies. Zinc nitride is a n-type semiconductor material having a direct band gap, and is not widely studied. Previous papers reported that zinc nitride is a n-type semiconductor having low resistivity and high electron mobility. Its band gap varies from 1.23 eV to 3.2 eV depending on the process condition. In this work, we successfully fabricated zinc nitride p-n junction by heat treatment on zinc nitride films. The threshold voltage of p-n junction is about 1 V. The Zinc nitride films were prepared by reactive RF magnetron sputtering. The as-grown zinc nitride thin film is a n-type material. It is found that the film treated at 300¢J for 3 hours can be changed to a p-type material. The zinc nitride has a very low resistance (2.2¡Ñ10-2 £[-cm) and high carrier concentration (3.88¡Ñ1019 cm-3) after the heat treatment. The optical band gap of zinc nitride was determined as a direct band gap varying from 1.1 eV to 1.6 eV according to the temperature of heat treatment. The zinc nitride was successfully prepared with various electrical characteristics and band gaps by controlling the temperature of heat treatment.

Integrated temperature sensors play an important role in enhancing the performance of on-chip power and thermal management systems in today's highly-integrated system-on-chip (SoC) platforms, such as microprocessors. Accurate on-chip temperature measurement is essential to maximize the performance and reliability of these SoCs. However, due to non-uniform power consumption by different functional blocks, microprocessors have fairly large thermal gradient (and variation) across their chips. In the case of multi-core microprocessors for example, there are task-specific thermal gradients across different cores on the same die. As a result, multiple temperature sensors are needed to measure the temperature profile at all relevant coordinates of the chip. Subsequently, the results of the temperature measurements are used to take corrective measures to enhance the performance, or save the SoC from catastrophic over-heating situations which can cause permanent damage. Furthermore, in a large multi-core microprocessor, it is also imperative to continuously monitor potential hot-spots that are prone to thermal runaway. The locations of such hot spots depend on the operations and instruction the processor carries out at a given time. Due to practical limitations, it is an overkill to place a big size temperature sensor nearest to all possible hot spots. Thus, an ideal on-chip temperature sensor should have minimal area so that it can be placed non-invasively across the chip without drastically changing the chip floor plan. In addition, the power consumption of the sensors should be very low to reduce the power budget overhead of thermal monitoring system, and to minimize measurement inaccuracies due to self-heating. The objective of this research is to design an ultra-small size and ultra-low power temperature sensor such that it can be placed in the intimate proximity of all possible hot spots across the chip. The general idea is to use the leakage current of a reverse-bias p-n junction diode as an operand for temperature sensing. The tasks within this project are to examine the theoretical aspect of such sensors in both Silicon-On-Insulator (SOI), and bulk Complementary Metal-Oxide Semiconductor (CMOS) technologies, implement them in deep sub-micron technologies, and ultimately evaluate their performances, and compare them to existing solutions. / text

Density functional theory is used to study the physico-chemical effects of two metallic thin films separated by distances in a range of 4-10 amperes. In this condition, the electrons from the metallic thin film surfaces tunnel through the energy barrier existing between the separated thin films, creating an electronic distribution in the gap between films. The characteristics and features of this electronic distribution, such as energy, momentum, and number of electrons, can be traced by quantum mechanical analyses. These same features can be tuned by varying metallic thin film properties like thickness, separation between films, and film chemical nature. The possibility to tune the physical properties of the electrons located in the gap between thin films makes the studied systems promising for applications that range from catalysis to nano-electronics. Molecular oxygen, water, and ethylene were located in the gap between thin films in order to study the physical and chemical effects of having those molecules in the gap between thin films. It was observed that the electron structure in the gap modifies the geometric and electronic structure of those molecules placed in the gap. In the case of molecular oxygen, it was found that the dissociation energy can be tuned by changing the separation between thin films and changing the chemical nature of the surface and overlayer of the thin film. For water, it was found that by tuning the chemical nature of the surface and sub-surface of both metallic thin films, molecular water dissociation can occur. When ethylene was located in the gap between Ti/Pt thin films, the molecule converts in an anion radical adopting the geometry and structure of the activated monomer necessary to initiate chain polymerization. Regarding magnetism, it was found that by the surface interaction between Ti/Pt and Pt thin films, the magnetic moment of the system decreases as the separation between thin films decreases. The phenomenon was explained by changes observed in the number of electronic states at the Fermi level and in the exchange splitting as a function of separation between films. Finally, a system that resembles a p-n junction was proposed and analyzed. The system is a junction of two metallic thin films with different electronic density in the gap between surfaces. These junctions can be the building blocks for many electronic devices.

La présente thèse décrit la préparation de complexes de Cu(I) stables grâce à l’ingénierie moléculaire de ligands permettant d’éviter la formation de plusieurs espèces en équilibre. Dans le cas de ligands P-N, la stratégie proposée repose sur l’utilisation d’un ligand ayant des substituants permettant de masquer un centre métallique et ainsi d’empêcher les réactions avec des nucléophiles permettant la dissociation du ligand. Dans le cas des dérivés [Cu(NN)(PP)]+, l’approche synthétique développée repose sur l’utilisation de ligands phénanthrolines macrocycliques empêchant la formation des complexes homoleptiques [Cu(NN)2]+ correspondant. Des complexes stables et luminescents ont ainsi été préparés, les rendements quantiques d’émission allant jusqu’à 46% à l’état solide pour les meilleurs luminophores. / The present PhD thesis descibes the preparation of stable Cu(I) complexes through appropriate ligand design to prevent the formation of several species in equilibrium. In the case of dinucleating P,N-ligands, the proposed strategy is based on the use of a ligand with additional substituents to shield the metal centers and thus to prevent nucleophilic attacks leading to ligand dissociation. In the case of the [Cu(NN)(PP)]+ derivatives, the proposed synthetic strategy relies on the use of macrocyclic phenanthroline ligands preventing the formation of the corresponding homoleptic complexes [Cu(NN)2]+. Stable luminescent complexes have been thus prepared, the emission quantum yields being as high as 46% in the solid state for the best emitters.

Ce travail de thèse porte sur la caractérisation à l'échelle du fil unique des propriétés de fils GaN de taille micronique (µfil), en vue du développement d'une technologie de diodes électroluminescentes (LEDs) à base d'une assemblée de µfils GaN crûs par épitaxie en phase vapeur aux organométalliques. Chaque µfil est lui-même une LED constituée d'un cœur de type n et d'une coquille de type p, entre lesquels est insérée une zone active composée de multi-puits quantiques InGaN/GaN. En premier lieu, les propriétés électriques des différentes régions du cœur de type n ont été analysées par des mesures de résistivité à l'échelle du fil unique. Le µfil GaN:Si fortement dopé possède une conductivité électrique jamais rapportée dans le cas de couches planaires comparables. Une approche originale combinant une mesure de résistivité et de propriétés thermoélectriques a alors été développée pour séparer les contributions de la densité d'électrons et de leur mobilité à température ambiante dans ces µfils. Des mesures optiques résolues spatialement de cathodoluminescence (CL) et µRaman confirment ces valeurs de densités d'électrons. Une seconde partie détaille une étude résolue spatialement des jonctions p-n cœur-coquille par des techniques à base d'un faisceau électronique. Sur un µfil clivé, la jonction tridimensionnelle (axiale et radiale) existante dans ces structures est mise en évidence par une cartographie du champ électrique (courant induit par faisceau électronique, EBIC) ou du potentiel électrostatique (contraste de tension des électrons secondaires). Ces techniques renseignent alors sur les niveaux de dopage donneur et accepteur et les longueurs de diffusion des porteurs minoritaires à proximité de la jonction. La cartographie EBIC décrit également l'état d'activation des dopants Mg dans la coquille p-GaN:Mg. Finalement, la combinaison de mesures EBIC et CL avec une étude des propriétés électro-optiques d'un µfil LED, fournit des voies d'optimisation pour la réalisation de LEDs à base de µfils plus efficaces. / This thesis deals with the characterization of GaN microwires (µwires) at the single wire level,toward the development of a light-emitting diode (LED) technology based on an ensemble of standing GaN µwires grown by metal organic vapour phase epitaxy. Each µwire is actually an LED consisting of an n-type core and a p-type shell, between which an InGaN/GaN multiquantum well active region is inserted. First, the electrical properties of the different parts of the n-type core were determined using resistivity measurements at the single wire level. The GaN:Si µwire exhibits conductivity values never reported by the planar layer counterparts. An original technique combining resistivity and thermoelectric measurements was developed to infer the electron density and mobility in these µwires. Spatially resolved optical measurements such as cathodoluminescence (CL) and µRaman confirmed the electron density values. The second part describes a spatially resolved study of the core-shell p-n junction using electron beam probing techniques. On a cleaved wire, the tridimensional (axial and radial) junction was highlighted by mapping the electric field (electron beam induced current, EBIC) or the electrostatic potential (secondary electron voltage contrast). These techniques yielded the donor and acceptor doping levels as well as the minority carriers diffusion lengths in the vicinity of the junction. EBIC mapping also provided the activation state of Mg dopants in the p-GaN:Mg shell. Finally, a study of the electro-optical properties of a single µwire LED, combined with EBIC and CL measurements, paves the way to the fabrication of more efficient µwire-based LED.