Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Silicon electronic properties

A photovoltaic cell (often called a solar cell) consists of layers of semiconductor materials with different electronic properties. In most of today s solar cells the semiconductor is silicon, an abundant element in the earth s crust. By doping (i.e., chemically introducing impurity elements) most of the silicon with boron to give it a positive or p-type electrical character, and doping a thin layer on the front of the cell with phosphorus to give it a negative or n-type character, a transition region between the two types... [Pg.1058]

The electronic properties of silicon and other semiconductor materials are shown in Table 13.2. [Pg.352]

The hydrogen abstraction from the Si-H moiety of silanes is fundamentally important for these reactions. Kinetic studies have been performed with many types of silicon hydrides and with a large variety of radicals and been reviewed periodically. The data can be interpreted in terms of the electronic properties of the silanes imparted by substituents for each attacking radical. In brevity, we compared in Figure 1 the rate constants of hydrogen abstraction from a variety of reducing systems by primary alkyl radicals at ca. 80°C. ... [Pg.124]

The recent interest in substituted silane polymers has resulted in a number of theoretical (15-19) and spectroscopic (19-21) studies. Most of the theoretical studies have assumed an all-trans planar zig-zag backbone conformation for computational simplicity. However, early PES studies of a number of short chain silicon catenates strongly suggested that the electronic properties may also depend on the conformation of the silicon backbone (22). This was recently confirmed by spectroscopic studies of poly(di-n-hexylsilane) in the solid state (23-26). Complementary studies in solution have suggested that conformational changes in the polysilane backbone may also be responsible for the unusual thermochromic behavior of many derivatives (27,28). In order to avoid the additional complexities associated with this thermochromism and possible aggregation effects at low temperatures, we have limited this report to polymer solutions at room temperature. [Pg.61]

ELECTRONIC PROPERTIES DOPED SILICON AND GERMANIUM AS EXAMPLES 7... [Pg.7]

The conditions for formation of PS on all types of substrates in terms of current density and HF concentrations were established by Zhang et al.18 by the end of 1980 s. Whether formation of PS occurs during anodization was found to be largely independent of the electronic properties of silicon such as doping type and concentration, but depend on the nature of electrochemical reactions. [Pg.148]

The electronic properties of silicon are essential in the understanding of silicon as an electrode material in an electrochemical cell. As in the case of electrolytes, where we have to consider different charged particles with different mobilities, two kinds of charge carriers - electrons and holes - are present in a semiconductor. The energy gap between the conduction band (CB) and the valence band (VB) in silicon is 1.11 eV at RT, which limits the upper operation temperature for silicon devices to about 200 °C. The band gap is indirect this means the transfer of an electron from the top of the VB to the bottom of the CB changes its energy and its momentum. [Pg.5]

In the early days of silicon device manufacturing the need for surfaces with a low defect density led to the development of CP solutions. Defect etchants were developed at the same time in order to study the crystal quality for different crystal growth processes. The improvement of the growth methods and the introduction of chemo-mechanical polishing methods led to defect-free single crystals with optically flat surfaces of superior electronic properties. This reduced the interest in CP and defect delineation. [Pg.23]

This is the regime of cathodic currents. The silicon atoms of the electrode do not participate in the chemical reaction in this regime. An n-type electrode is under forward bias and the current is caused by majority carriers (electrons). The fact that photogenerated minority carriers (holes) are detectable at the collector indicates that the front is under flat band or accumulation. A decrease of IBC with cathodization time is observed. As Fig. 3.2 shows, the minority carrier current at the collector after switching to a cathodic potential is identical to that at VQcp in the first moment, but then it decreases within seconds to lower values, as indicated by arrows in Fig. 3.2. This can be interpreted as an increase of the surface recombination velocity with time under cathodic potential. It can be speculated that protons, which rapidly diffuse into the bulk of the electrode, are responsible for the change of the electronic properties of the surface layer [A17]. However, any other effect sufficient to produce a surface recombination velocity in excess of 100 cm s 1 would produce similar results. [Pg.45]

Contamination of silicon wafers by heavy metals is a major cause of low yields in the manufacture of electronic devices. Concentrations in the order of 1011 cm-3 [Ha2] are sufficient to affect the device performance, because impurity atoms constitute recombination centers for minority carriers and thereby reduce their lifetime [Scl7]. In addition, precipitates caused by contaminants may affect gate oxide quality. Note that a contamination of 1011 cnT3 corresponds to a pinhead of iron (1 mm3) dissolved in a swimming pool of silicon (850 m3). Such minute contamination levels are far below the detection limit of the standard analytical techniques used in chemistry. The best way to detect such traces of contaminants is to measure the induced change in electronic properties itself, such as the oxide defect density or the minority carrier lifetime, respectively diffusion length. [Pg.211]

As described above, silicon crystals can be grown from a variety of gas sources. Because the rate of growth can be modulated using these techniques, dopants can be efficiently incorporated into a growing crystal. This results in control of the atomic structure of the crystal, and allows the production of samples which have specific electronic properties. The mechanisms by which gas-phase silicon species are incorporated into the crystal, however, are still unclear, and so molecular dynamics simulations have been used to help understand these microscopic reaction events. [Pg.317]


See other pages where Silicon electronic properties is mentioned: [Pg.87]    [Pg.58]    [Pg.123]    [Pg.77]    [Pg.252]    [Pg.3]    [Pg.3]    [Pg.114]    [Pg.47]    [Pg.94]    [Pg.2]    [Pg.3]    [Pg.314]    [Pg.590]    [Pg.362]    [Pg.16]    [Pg.25]    [Pg.128]    [Pg.417]    [Pg.427]    [Pg.455]    [Pg.77]    [Pg.352]    [Pg.7]    [Pg.489]    [Pg.123]    [Pg.65]    [Pg.134]    [Pg.1]    [Pg.158]    [Pg.136]    [Pg.31]   
See also in sourсe #XX -- [ Pg.552 , Pg.581 ]

See also in sourсe #XX -- [ Pg.488 ]

See also in sourсe #XX -- [ Pg.504 ]

See also in sourсe #XX -- [ Pg.589 , Pg.590 , Pg.591 , Pg.592 , Pg.593 ]

See also in sourсe #XX -- [ Pg.589 , Pg.590 , Pg.591 , Pg.592 , Pg.593 ]




SEARCH



Electronic silicone

Silicones properties

© 2024 chempedia.info