Gallium phosphide

Gallium Phosphide.—Nakato et al. 1 2-166 series of papers, have discussed the complicated surface properties of n-GaP. The main problem encountered with 

Vainas, G. Modes, J. Manassen, and D. Cahen, Appl. Phys. Lett., 1981, 38, 458. 

Butler and Ginley have explored the properties of p-GaP in some detail. The stability of the material in acid and base solutions is poor, and the photoresponse is seriously reduced by the presence of surface states, which act as efficient recombination centres. Additional evidence for these surface states comes from measurements of the sub-band-gap response of GaP photoelectrodes, and Butler and Ginley argue convincingly that the same bulk state controls the electroluminescence efficiency of GaP. 

DeMattei,etal. (69), in a limited study in 1978, studied the conditions necessary for the stable growth of GaP epitaxial layers on Si and GaP substrates. They identified the variables critical to controlling the morphology and uniformity of electrodeposited GaP layers. They used the same fused salt composition and range of deposition temperatures (750 - 900°C) as Cuomo and Gambino. The electrochemical cell reactions for GaP at the cathode were probably  

This reactivity of silicon with the melt and the poor thermal expansion mismatch between Si and GaP, which was probably responsible for the cracking observed by Cuomo and Gambino (68), led DeMattei, et al. (69), to study the homoepitaxy of GaP on GaP substrates. The minimum deposition potentials for GaP on (111) GaP at 800°C and at 900°C are shown In Table 1, along with data for the eiectrodeposition of GaP on Si and graphite substrates at 900°C. 

Minimum Deposition Potentials for GaP on Various Cathodic Materials 

Both the preliminary work of Cuomo and Gambino (68), and DeMattei, et al. (69), have shown that electrodeposition of GaP is possible. More carefully controlled systematic experiments should lead to much improved epitaxial deposits. It is not likely, however, considering the major advances of vapor deposition techniques, that astrong need for this technology will be forthcoming. 

---

The lasers in the 670-nm region, from the aluminum indium gallium phosphide [107102-89-6] system are available at center wavelengths from 635 to 690 nm. These wavelengths He at the red end of the visible spectmm. Such lasers, which may compete for appHcations with the helium—neon laser, are under intensive development and represent less mature technology than the other lasers. 

A mixture of (C H ) , TiCl, and AlCl is useful for polymerizing C —olefins (85). The dimerization of propylene is accompHshed by using catalysts such as Ni(PR2)4 (86). Alkylphosphines such as / fZ-butylphosphine [2501-94-2] have been proposed as a substitute for high purity phosphine in the production of the semiconductor gallium phosphide (87). 

LED materials include gallium arsenic phosphide, gallium aluminum arsenide, gallium phosphide, gallium indium phosphide, and gallium aluminum phosphide. The preferred deposition process is MOCVD, which permits very exacting control of the epitaxial growth and purity. Typical applications of LED s are watches, clocks, scales, calculators, computers, optical transmission devices, and many others. 

Photodetectors operate by carrier transport across a semiconductor junction. A wide variety of these photodiodes are available, such as Schottky diodes, phototransistors, and avalanche photodetectors. Typical photodetector materials are gallium arsenic phosphide and gallium phosphide, which are produced by MOCVD or MBE. 

Benniston AC, Haniman A (2008) Artificial photosynthesis. Materials Today 11 26-34 Inoue T, Fujishima A, Konishi S, Honda K (1979) Photoelectrocatalytic reduction of carbon dioxide in aqueous suspensions of semiconductor powders. Nature 277 637-638 Halmann M (1978) Photoelectrochemical reduction of aqueous carbon dioxide on p-type gallium phosphide in liquid junction solar cells. Nature 275 115-116 Heminger JC, Carr R, Somorjai GA (1987) The photoassisted reaction of gaseous water and carbon dioxide adsorbed on the SrH03 (111) crystal face to form methane. Chem Phys Lett 57 100-104... 

Gallium Nitride, GaN or Gallium Phosphide, GaP Ultraviolet and Blue... 

A further interesting feature of the gallium phosphides and arsenides is that the former compounds are colorless whereas the latter range from yellow to orange. Color can arise from ir- ir transitions in main group compounds for example, in the disilylenes and digermenes R2E = ER2 (E = Si, Ge) in which the it- tt transitions occur at lower energy than... 

M. Halmann. Photoelectrochemical reduction of aqueous carbon dioxide on p-type gallium phosphide in liquid junction solar cells. Nature. 1978, 275(5676) 115-116. 

Gallium phosphide semiconductor band structure of, 22 142—143 in LED technology, 22 175 Gallium production, economic aspects of, 72 348-349... 

Phosphorus (P), 19 1-19. See also GaAsP system Gallium phosphide (GaP) semiconductor InGaAsP alloy Organophosphorus extractants Phosphate fertilizers atomized, 18 820... 

Nitrides, phosphides, carbides Aluminum phosphide, calcium carbide, gallium phosphide... 

Figure 12.20 shows the structure of the side-window circular cage type and linear focused head-on type of photomultiplier which are both preeminent in fluorescence studies. The lower cost of side-window tubes tends to favor their use for steady-state studies, whereas the ultimate performance for lifetime studies is probably at present provided by linear focused devices. In both types internal current amplification is achieved by virtue of secondary electron emission from discrete dynode stages, usually constructed of copper-beryllium (CuBe) alloy, though gallium-phosphide (GaP) first dynodes have been used to obtain higher gains. 

Figure 5-47 shows the Mott-Schottky plot of n-type and p-type semiconductor electrodes of gallium phosphide in an acidic solution. The Mott-Schottl plot can be used to estimate the flat band potential and the effective Debye length I D. . The flat band potential of p-type electrode is more anodic (positive) than that of n-type electrode this difference in the flat band potential between the two types of the same semiconductor electrode is nearly equivalent to the band gap (2.3 eV) of the semiconductor (gallium phosphide). 

Fig. 6-47. Mott-Schottky plot of electrode capacity observed for n-type and p-type semiconductor electrodes of gallium phosphide in a 0.05 M sulfuric add solution. [From Meouning, 1969.]...

Fig. 10-17. Polarization curves for cathodic h3 drogen redox reaction on a photoexdted p-type semiconductor electrode of gallium phosphide equilibrium potential of...

Fig. 10-31. Energy diagram for a photoelectrolytic cell of decomposition of water consisting of a p-type cathode of gallium phosphide and an n-type anode of titanium oxide.

Lubberhuizen WH, Vanmaekelbergh D, Van Faassen E (2000) Recombination of photogenerated charge carriers in nanoporous gallium phosphide. J Porous Mater 7 147-152... 

Various inorganic semiconductors (p-type and/or n-type nonoxide semiconducting materials) sucb as amorphous or crystalline silicon (a-Si or c-Si), gallium arsenide (GaAs), cadmium telluride (CdTe), gallium phosphide (GaP), indium phosphide (InP), copper... 

Ellis AB, Bolts JM, Kaiser SW, Wrighton MS (1977) Study of n-type gallium arsenide- and gallium phosphide-based photoelectrochemical cells. Stabilization by kinetic control and conversion of optical energy into electricity.99 2948-2853... 

Gallium arsenide is produced in polycrystaUine form as high purity, single crystals for electronic applications. It is produced as ingots or alloys, combined with indium arsenide or gallium phosphide, for semiconductor apphcations. 

Elemental composition Ga 69.24%, P 30.76%. Gallium phosphide may be characterized hy its physical and electronic properties. It may also he analyzed hy various x-ray methods. Gallium may he measured hy AA and ICP spectrophotometry following digestion with nitric acid or aqua regia and appropriate dilution (See Gallium). 

---