Gallium surface structure

Electrochemical Behavior and Surface Structure of Gallium Phosphide Electrodes... 

For comparison of the TEs for stoichiometrically different surface structures, the TEs are usually plotted versus the chemical potential A/r of one of the elements (usually the cation) in a surface phase diagram. As an example, in Figure 13.17, the calculated TE of different reconstructions on a GaAs(OOl) as a function of the chemical potential A/r(Ga) of gallium with respect to its bulk value are shown. Eor GaAs, — AH(AB) has a value of (0.80 0.15)eV, referred to As-rich conditions. We obtain for the lower and upper limits —0.8 < A/r(Ga) < 0. These... 

Figure 13.17 Calculated phase diagram for different GaAs(OOl) surface structures displaying the total surface energy per (1x1) unit cell versus the variation of the gallium chemical potential A/x(A) with respect to the bulk value (From Refs. [50].). The stable surface structures are at the lower border of the phase diagram.

The actual structure at a vapor-liquid interface can be probed with x-rays. Rice and co-workers [72,73,117] use x-ray reflection to determine the composition perpendicular to the surface and grazing incidence x-ray diffraction to study the transverse structure of an interface. In a study of bismuth gallium mixtures. 

Shimizu, K Takamatsu, M Nishi, K Yoshida, H Satsuma, A Tanaka, T Yoshida, S Hattori, T. Alumina-supported gallium oxide catalysts for NO selective reduction Influence of the local structure of surface gallium oxide species on the catalytic activity, J. Phys. Chem., B, 1999, Volume 103, Issue 9, 1542-1549. 

Since discovery of MCM-41 materials [1,2] many researchers have been concentrated on the improvement of their quality and properties by incorporating heteroatoms such as titanium [3-5], boron [6,7], vanadium [8], gallium [9], and recently lanthanides (mainly La and Ce) [10-13]. Incorporation of these elements into the MCM-41 structure influences its stability as well as adsorption and catalytic properties [13]. The presence of silanol groups on the surface of these mesoporous materials allows for bonding of organic and inorganic ligands [14-16]. 

Gallium arsenide s native oxide is found to be a mixture of nonstoichiometric galhum and arsenic oxides and elemental arsenic. Thus, the electronic band structure is found to be severely disrupted, causing a breakdown in normal semiconductor behavior on the GaAs surface. As a consequence, the GaAs MISFET (metal insulator semiconductor field-effect transistor) equivalent to the technologically important Si-based MOSFET (metal-oxide semiconductor field-effect transistor) is, therefore, presently unavailable. 

Mixed y-Ga203-Al203 oxides of different stoichiometry were prepared by the solvothermal method from Ga(acac)3 and Al(OPr-i)3 as starting materials and were used as catalysts for selective reduction of NO with methane. The initial formation of gallium oxide nuclei controls the crystal structure of the mixed gallium-aluminum oxides. It is found that the acid density per surface area is independent of the Al Ga feed ratio but depends on the reaction medium (diethylenetriamine, 2-methylaminoethanol, toluene, 1,5-pentanediol etc.), whereby in diethylenetriamine the catalyst had lower densities of acid sites and showed a higher methane efficiency. 

The structures with self-organized GaN/AlN QDs were grown by molecular beam epitaxy (MBE) on (0001) sapphire substrates. Ammonia was used as the source of active nitrogen. A single layer of GaN QDs was formed on the AIN buffer surface by a particular MBE growth mode at relatively low substrate temperatures (Ts 540°C). A beam equivalent pressure (BEP) of gallium flux was 5.4T0 Torr and BEP of ammonia flux was 10" Torr. To obtain GaN QDs... 

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