Phosphorus doping compounds

It has been seen in the previous section that the ratio of the onsite electron-electron Coulomb repulsion and the one-electron bandwidth is a critical parameter. The Mott-Hubbard insulating state is observed when U > W, that is, with narrow-band systems like transition metal compounds. Disorder is another condition that localizes charge carriers. In crystalline solids, there are several possible types of disorder. One kind arises from the random placement of impurity atoms in lattice sites or interstitial sites. The term Anderson localization is applied to systems in which the charge carriers are localized by this type of disorder. Anderson localization is important in a wide range of materials, from phosphorus-doped silicon to the perovskite oxide strontium-doped lanthanum vanadate, Lai cSr t V03. 

The plasma jet can be cooled rapidly just prior to coming in contact with the substrate by using a blast of cold inert gas fed into an annular fixture. Gaseous boron or phosphorus compounds can be introduced into the gas feed for the deposition of doped-semiconduc-tor diamond. 

Both compounds crystallize with the cadmium diiodide structure (space group P3ml) as previously reported on polycrystalline samples.3 For platinum disulfide, ao = 3.542(1) A and c0 = 5.043(1) A, and for platinum ditelluride, a0 = 4.023(1) A and c0 = 5.220(3) A. Direct chemical analysis for the component elements was not carried out. Instead, precision density and unit-cell determinations were performed to characterize the samples. The densities of both compounds as determined by a hydrostatic technique with heptadecafluorodeca-hydro-l-(trifluoromethyl)naphthalene as the density fluid4 indicated that they are slightly deficient in platinum. For platinum disulfide, = 7.86 g/cm3 and Pmeas = 7.7(1) gm/cm3, and for platinum ditelluride, p = 10.2 gm/cm3 and Pmeas = 9.8(1) gm/cm3. In a typical experiment an emission spectrum of the platinum disulfide showed that phosphorus was present in less than 5 ppm. A mass spectroscopic examination of the platinum ditelluride revealed a small doping by sulfur (less than 0.4%) and traces of chlorine and phosphorus (less than 100 ppm). 

The determination of specific phosphorus compounds in thin films is important. Only through wet chemical analysis was it possible to first discover the presence and then to accurately measure the quantities of P2Os, P203, and phosphine found in plasma, plasma-enhanced, LPO-LTO (low-pressure oxide-low-temperature oxide), and CVD (chemical vapor deposition) processes (3). Methods such as X-ray or FTIR spectroscopy would have seen all phosphorus atoms and would have characterized them as totally useful phosphorus. In plasma and plasma-enhanced CVD films, phosphine is totally useless in doping processes. 

In order to realize junction 4ight-emitting diodes (LEDs) having the same structure as that of practical III-V compound semiconductor LEDs, we must achieve n- and p-type conductivity control. The phosphorus and boron doping, which is known to be effective for obtaining high-conductivity n- and p-type a-Si H, respectively, seems to be less effective for the... 

Composites, in the usual sense, were proposed to improve the mechanical stability of the electrode. An example is 80 wt% coke powder in PVC [192]. Of greater interest are carbons with nanodispersed boron (via BCI3, 900 °C). The compound B0.17C0.83 has a reversible specific capacity of 437 Ah/kg [193]. An even stronger enhancement of ilTs, up to 500 Ah/kg could be achieved by silicon (via SiCLj/via Me2Cl2Si, 950 °C) for the composition Si0.nC0.g9 [194,195]. Structural aspects are compiled in Fig. 22. The improved stoichiometry is attributed to the electron-acceptor capability of boron or silicon. Doping of petroleum-fuel green coke by phosphorus elevates by 20% [191]. 

Silicon wafers doped with phosphorus (resistivity 0.1 D. cm) have been used as substrates. A composite aluminum+silicon (Al+Si) films were fabricated by magnetron sputtering of a compound target containing 45 at. % of Si and 55 at. % of Al. The films thickness was varied in the range of 20-140 nm. Then... 

Silicon s most familiar use is in the production of microprocessor chips. Computer microprocessor chips are made from thin slices, or wafers, of a pure silicon crystal. The wafers are doped with elements such as boron, phosphorus, and arsenic to confer semiconducting properties on the silicon. A photographic process places patterns for several chips onto one wafer. Gaseous compounds of metals are allowed to diffuse into the open spots in the pattern, and then the pattern is removed. This process is repeated several times to build up complex microdevices on the surface of the wafer. When the wafer is finished and tested, it is cut into individual chips. 

Some yttrium compounds, such as Y3AI5O12 and (YAG), have good luminescence properties which are useful in the production of solid-state lasers with wavelengths of 1.06 pm and 0.53 pm and an output of 1800 W (Kirk-Othmer 1999). Gr-doped Y3AI5O12 (YAG-Cr) increased their emission intensity with increasing firing temperature and the intensities observed for phosphorus powder (Matsubara et al. 

Silicon of high purity, normally p-type, is the basic material for this detector type. As with surface-barrier detectors, the silicon piece has the shape of a thin wafer. A thin layer of n-type silicon is formed on the front face of the wafer by applying a phosphorus compound to the surface and then heating the assembly to temperatures as high as 800-1000° C for less than an hour. The phosphorus diffuses into the silicon and dopes it with donors (Fig. 7.20). The n-type silicon in front and the p-type behind it form the p-n junction. 

Doping can be realized by adding compounds of boron or phosphorus [23]. 

If the pressure P and temperature T are fixed, then the total concentrations of point defects at thermodynamic equilibrium in a compound with n components can only be dependent upon the n — 1) independent chemical potentials fXi of the components (i.e. upon the (n — 1) component activities <2.). For example, the concentration of electronic defects in silicon that has been doped with aluminum (or phosphorus) is uniquely determined by the activity of the dopant element, since this is a binary system. In a completely analogous way, the concentrations of electron holes and cation vacancies in NiO are uniquely dependent upon the oxygen partial pressure as long as overall equilibrium can be assumed. 

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