Boule

Interest in AIN, GaN, InN and their alloys for device applications as blue light-emitting diodes and blue lasers has recently opened up new areas of high-pressure synthesis. Near atmospheric pressure, GaN and InN are nnstable with respect to decomposition to the elements far below the temperatures where they might melt. Thus, large boules of these materials typically used to make semiconductor devices caimot be grown from the... 

Whereas the OVD, PCVD, and MCVD processes build a refractive index profile layer by layer, the VAD process uses gaseous constituents in the flame to control the shape and temperature distribution across the face of the growing soot boule. 

Purified polycrystalline CVD siUcon from this reaction is then melted and a single-crystal boule weighing as much or more than 50 kg, and having a diameter up to 20 cm, is pulled from the melt by C2ochralski growth (8). Metallurgical-grade siUcon is not sufficientiy pure for appHcations in electronics... 

Of course, the most reliable and accurate method of quantitative analysis is to calibrate each element with standards prepared in matrices similar to the unknown being analyzed. For a survey technique that is used to examine such a wide variety of materials, however, standards are not available in many cases. When the technique is used mainly in one application (typing steels, specifying the purity of alloys for a selected group of elements, or identifying impurities in silicon boules and... 

NAA has been used to determine trace impurities in polysilicon, single-crystal boules, silicon wafers, and processed silicon, as well as plastics used for packaging. ... 

An example of an analysis done on polysilicon and single-crystal Czochralski silicon (CZ) is shown in Table 1. As can be seen, polysilicon, which was used to grow the crystal, is dirtier than the CZ silicon. This is expected, since segregation coefficients limit the incorporation of each element into the crystal boule during the crystal growth process. All values shown in the table are from bulk analysis. Table 2 shows NAA data obtained in an experiment where surface analysis was accom-... 

The growing crystal, or boule, is a cylinder supported by its vertical axis. The top of the crystal is kept molten by impinging a flame upon it. Fine adjustment of the head is not critical because the diameter of the boule can change to accommodate variations in heat input. 

There are four principal processes that may be used to manufacture the glass body that is drawn into today s optical fiber. "Outside" processes—outside vapor-phase oxidation and vertical axial deposition— produce layered deposits, of doped silica by varying the concentration of SiCl4 and dopants passing through a torch. The resulting "soot" of doped silica is deposited and partially sintered to form a porous silica boule. Next, the boule is sintered to a pore-free glass rod of exquisite purity and transparency. 

D. J., Douglas C. L, Boules M., Stewart J.A., Zhao L., Lacy B., Cusack B., Fauq A., Richelson E. Peptide nucleic acids targeted to the neurotensin receptor and administered i.p. cross the blood-brain barrier and specifically reduce gene expression. Proc. Natl Acad. Sci. USA 1999 96 7053-7058. 

Graded doses ofthe test substance are incorporated into broth dispensed in McCartney boules and the bottles inoculated with the test organism and incubated. The point at which no growth occurs is taken as the bacteriostatic concentration (minimum inhibitory concentration, MIC). It is essential when performing these tests to determine the size of the inoculum as the position of the end-point varies considerably with inoculum size, which should always be defined in any description of result. 

The problems of obtaining a seed-crystal 2ire not simple. We can freeze the melt to a polycrystalline state. When cool, we examine the boule (after first removing the crucible) to try to find a single crystal Icurge enough for a seed ( 3-6 mm.). We could also cast the melt into a mold and then look for seeds. We could also freeze a polycrystalline rod by pulling it... 

In this case, the whole mass can be made to freeze nearly instantaneously. It is this method which is currently being used to manufacture sapphire boules as leirge as 12 inches in diameter. The boule is then cut into slabs... 

Megharaj M, A Jovcic, HE Boul, JH Thiele (1997) Recalcitrance of l,l-dichloro-2,2-bis(p-chlorophenyl) ethylene (DDE) to cometabolic degradation by pure cultures of aerobic and anaerobic bacteria. Arch Environ Contam Toxicol 33 141-146. 

Aislabie J, AD Davison, HL Boul, PD Franzmann, DR Jardine, P Karuso (1999) Isolation of Terrabacter sp. strain DDE-1, which metabolizes l,l-dichloro-2-2-bis(4-chlorophenyl)ethylene when induced with biphenyl. Appl Environ Microbiol 65 5607-5611. 

Boul, M., Nyvlt and Sohnel (1981) Solubility of Inorganic Two-Component Systems (Elsevier). 

Walter, M., Boul, L., Chong, R., and Ford, C., Growth substrate selection and biodegradation of PCP by New Zealand white-rot fungi, J. Environ. Manage., 71, 361-369, 2004. 

Walter M, Boyd-Wilson K, Boul L, Ford C, McFadden D, Chong B, Pinfold J (2005) Int Biodeter Biodegr 56 51... 

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