Gallium arsenide

Spray pyrolysis is basically a thermal reaction between clusters of the liquid/vapor-atoms of different chemical species. The spray pyrolysis technique involves spraying of aqueous solution in spray form containing a decomposable salt solution of the constituent atoms. The experimental setup used in the present study is described elsewhere [21]. CdO thin films with different Cr- doping concentrations were deposited on ultrasonically cleaned microscopic glass substrates. The appropriate quantity of cadmium acetate dihydrate {(CH3 COO)2 •Cd•2H2O} was measured to make a 0.05 M solution by dissolving in 50 ml of deionised water and methanol in 1: 1 ration. The required amount of Chromium trichloride hexahydrate (CrCl3 • 6H2O), depending on the desired doping concentrations (0.25 wt. %, 0.50 wt. %, 0.75 wt. %, and 1.0 wt. %) was mixed with precursor solution. The resulting solution was sprayed on the glass substrates preheated to 300 ˚C. Chromel–alumel thermocouple was used to measure the substrate temperature, by placing at the center of the hot plate using a digital INDFUR PID temperature controller, with an accuracy of ± 5 C. The nozzle-substrate distance was kept fixed at 30 cm for all the experiments. Spray gun was kept at an angle of 45; a compressed, regulated and filtered air at a pressure of 45 kg/cm2 was used as the carrier gas. Numerous films were deposited by varying the substrate temperature, solution concentration, dopant concentration, spray angle, spray rate,…

The substrate is rotated in the center of the growth chamber to ensure even growth on its surface and its angle can be manipulated depending on which effusion chamber shutter is opened. The time the substrate is exposed to an effusion chamber is calculated. Based on the area of the substrate, the pressure in the chamber and the molecular weight of the species, the shutter time is calculated to ensure the desired thickness of the film which will be adsorbed on to the substrate. For example, when…

Gallium is one of those elements that is used in industry every day. Gallium was discovered in Paris at the private laboratory of Paul-Emile Lecoq de Boisbaudran (1831-1912) at 3 a.m. on August, 1875. He observed a new violet line in the atomic spectrum of some zinc he had extracted from a sample of zinc blende ore (ZnS) from the Pyrenees. He knew it meant that an unknown element was present. Gallium comes from Gallia, the Latin name for France. Gallium also has origins in the Latin word Gallus.…

discovery of PV, photovoltaics, happened in 1839, a researcher found that certain materials could produce energy if exposed to light. This discovery later led to photovoltaic cells being produced as a type of energy production. The cells were not viable until space researchers/engineers realized that PV cells would be a good way to produce electricity in space. That led to more research and therefor less cost because it was being made better with every discovery. The first space station to use…

Figure1.3: Band gap vs lattice constants diagram for hexagonal nitride compounds. The typical of measured band gap bowing for ternary alloys AlGaN and InGaN is shown by the solid line track[21]. 1.4. Unique Material properties of Gallium Nitride: The unique material properties of GaN engraves it as an prominent semiconductor material for many electronic and optoelectronic devices[18]. • The wide and direct energy band gap sorts GaN as an appropriate materials for device fabrication in the field…

(Pimentel, 2002, p. 1111). While climate change cannot be stopped, it can be slowed down by limiting the amount of carbon dioxide gas that is released into the atmosphere. An issue, other than global warming, is that by burning so much carbon dioxide, holes are beginning to form in the stratosphere, the section that protects the earth the most from the harmful ultra Violet rays from the sun. These rays are great for energy but cause sun burn and in extreme cases skin cases or sun poisoning. So,…

mainstream solution today. They do not consume it to produce heat, as incandescent bulbs do, and last much longer, with new designs lasting over 50,000 hrs! This means fewer visits to the store to replace burned out bulbs. Coupled with the fact that they emit directional light, it is obvious that LED light bulbs are the smarter, leaner, greener choice. HISTORY- LED lighting started with extensive research in the early 60's. Texas Instruments, General Electric, & RCA Labortories…

which are the precursors for the deposition of transitional metals and their compounds. However, organo-metals, in some situation, also include compounds of elements, such as silicon, phosphorus, arsenic, selenium and tellurium, that are not considered as metallic. 2.2.2 The process of OMCVD The main process of OMCVD is similar to the CVD processes. Due to the high temperature or other energy supply, the organo-metals precursors are evaporated in the reaction chamber and decompose, usually…

produced is around 25 to 50 watts. However, most homes and buildings have multiple panels, so some appliances are capable of being powered by solar panels. But, this doesn’t answer the initial question of are solar panels energy efficient? To explore this further, we need to address the material the solar cells are made from, the amount of time these panels are utilized, and what effect the environment plays in a solar panels efficiency. Getting back to solar cells, it is important to know what…

Using such cells would be economical where the panel space is not at a premium. Another way to minimize the waste is to grow crystals on ribbons. Some U.S. companies have set up plants to draw pv ribbons, which are then cut by laser to reduce waste. 5.3.2 POLYCRYSTALLINE AND SEMI CRYSTALLINE The process cost is low and fast relatively to manufacture thick crystalline cells. Instead of drawing single crystals using seeds, the molten silicon is cast into ingots. In the process, it forms multiple…