Effect of Traps

The effect of traps on the SCLC has been widely studied, both theoretically and experimentally. In the case of a single shallow trap level of density lyii g at an energy E below the conduction band (or above the valence band), the current is simply multiplied by a factor 9 - nf/( f -f- t) where and t are the density of free and trapped carriers, respectively. In the case where tif n, and assuming that the carrier distribution follows a simple Boltzmann statistic, 9 is given by 

The case of an exponential distribution of traps has been extensively developed by Mark and Helfrieh [51], Such a distribution is characterized by the function 

As stated in the previous section, the standard SCLC theory, as developed by Lampert and Mark and Helfrieh, neglects the carrier diffusion. A more comprehensive theory, also including an exponential distribution of traps, has been elaborated 

It must be stressed again that this Unear current does not correspond to the conventional ohmic current it appears in materials completely devoid of free carriers, and is only due to carriers injected from the metal electrodes at both sides of the insulator. In other words, the linear current has the same origin as the more classical space charge limited current observed at higher voltages. We note once more that the space charge limited linear current differ from the conventional ohmic ciurent through its temperature and film thickness dependence. 

At high voltages, the current voltage curve merges with that predicted by the standard SCLC theory, Eqs (30) and (34). 

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Ewsuk K G 1992 Effects of trapped gases on ceramic-fiiied-giass composite densification Solid State Phenomena voi 25-26, ed A C D Chakiader and J A Lund (Brookfieid, VT Trans-Tech) pp 63-72 (Proc. Sintering 91)... 

The variation of o,.jj with trap depth is presented in Figure 12-19. The effect of traps on the mobility, reflected in an increase of acjj, becomes noticeable only above a certain critical trap depth that depends on concentration. Above that critical value, a2,.), increases approximately linearly with ,. Figure 12-20 shows complementary information concerning the effect of the trap concentration on a,. at constant trap depth. The data reproduces as a family of parallel straight lines on a (Pr/jlo)2 versus In c plot. Their intersection with the ov)jla— 1 tine indicates the critical concentration c, of traps of depth , needed to effect the mobility (see Fig. 12-21). 

The effect of traps on charge carrier motion does not become noticeable until the trap concentration reaches a threshold value. One can define a critical concentration Ci/2 at which the mobility has decreased to one half of the value of the trap-free system. Eq. (12.19) predicts that. ... 

It is remarkable that the magnitude of trapping is comparable to that in a system devoid of disorder. In fact, the critical concentration above which the effect of traps becomes noticeable is the same, i.c. In c, EJkT, which follows from Eq. (12.17). The basic difference between a disordered and a disorder-free system is... 

Figure 4.11 Transient current and voltage waveforms showing effect of trapping and detrapping, (a) No trapping, (b) Trapping, no detrapping, (c) Trapping and detrapping (from Ref. [13]).

Yencho then constructed the initial version of the machine and explored the parameters necessary to successfully form flaw-free parts. A key finding concerned the effects of trapped moisture. Despite the generally hydrophobic nature of PEEK, it was found that small amounts of moisture absorbed by the Gr/PEEK laminates subsequent to their manufacture converted into steam during the forming operation and caused extensive delamination. This was in... 

Up until now we have ignored the effects of trapping, i.e., the capture and slow release of electrons by centers lying above F, or of holes by centers below Ef. It is easy to include these effects formally if hole emission and capture are ignored, at first, then... 

Hoskins and Soffer (117) measured the fluorescent lifetime of the neodymium 4Fy2 state in yttrium oxide. They found a value of approximately 260 /zsec both at room temperature and at liquid-nitrogen temperature. They also observed a weaker long-lived component in the decay. They were unable to say whether this was evidence for a low-transition-probability ion site, or an effect of trapping of the resonance radiation near 0.9 /x. They report laser action, with a threshold of 260joules. This is a fairly high value for most crystalline materials. 

Williams, R.N., Fickle, D. S., Bartelt, R. J. and Dowd, P.F. (1993). Responses by adult Nitidulidae (Coleoptera) to synthetic aggregation pheromones, a coattractant, and effects of trap design and placement. Eur. J. Entomol., 90, 287-294. 

For PCDD/F removal, overall removal efficiency across the scrubber unit was determined, masking any catalytic effect of trapped flyash. Flowever, the tests did identify an increase in PCDD/F concentration in the flue gas with an increase in gas temperature, in the region 100-200°C. 

Figure 3. Effect of trapped charges or adsorption on energy diagrams of...

Figure 23 Chondrite-normalized abundances of REEs in representative harzburgites from the Oman ophiolite (symbols—whole-rock analyses), compared with numerical experiments of partial melting performed with the Plate Model of Vemieres et al. (1997), after Godard et al. (2000) (reproduced by permission of Elsevier from Earth Planet. Set Lett. 2000, 180, 133-148). Top melting without (a) and with (b) melt infiltration. Model (a) simulates continuous melting (Langmuir et al., 1977 Johnson and Dick, 1992), whereas in model (b) the molten peridotites are percolated by a melt of fixed, N-MORB composition. Model (b) is, therefore, comparable to the open-system melting model of Ozawa and Shimizu (1995). The numbers indicate olivine proportions (in percent) in residual peridotites. Bolder lines indicate the REE patterns of the less refractory peridotites. In model (a), the most refractory peridotite (76% olivine) is produced after 21.1% melt extraction. In model (b), the ratio of infiltrated melt to peridotite increases with melting degree, from 0.02 to 0.19. Bottom modification of the calculated REE patterns residual peridotites due to the presence of equilibrium, trapped melt. Models (c) and (d) show the effect of trapped melt on the most refractory peridotites of models (a) and (b), respectively. Bolder lines indicate the composition of residual peridotites without trapped melt. Numbers indicate the proportion of trapped melt (in percent). Model parameters...

Fig. 6. Effect of trapping potential on the detection of O and 0 ions formed from carbon monoxide in the om atron mass spectrometer. (After Stuckey )...

Fig. 4. The effect of trap shape on seal leakage, (a) Explanation of the trap shape factor, C. High C traps have larger volumes than low C traps with the same hydrocarbon column length, h. (b) Hydrocarbon flux into the trap over a 60 My period, (c) Volume of oil in the traps after 60 Ma, as a function of (M)/A/ and trap shape C, where k is permeability in m, A is leak area in m and Af is the seal thickness. Flux rate into the trap is typical for the central North Sea. Note the relatively narrow range of parameters leading to a dynamically stable, underfilled trap.

In this section we review the important theoretical developments relevant to host-sensitized energy transfer. The basic interaction between two isolated ions or molecules is discussed first, then the effects of having an ensemble of sensitizer and activator ions is presented. The mathematical description of energy transfer by multi-step migration among sensitizer ions is developed and the effects of trapping at activator sites is discussed. The importance of phonons in both single-step and multi-step transfer processes is also described. 

In the liver, kidney, and intestine, fructose can be converted to glycolytic/ gluconeogenic intermediates by the actions of three enzymes—fructokinase, aldolase B, and triokinase (also called triose kinase)—as shovra in Figure 24-1. In these tissues, fructose is rapidly phosphorylated to fructose 1-phosphate (FIP) by fructokinase at the expense of a molecule of adenosine triphosphate (ATP). This has the effect of trapping fructose inside the cell. A deficiency in this enzyme leads to the rare but benign condition known as essential fmcto-suria. In other tissues such as muscle, adipose, and red blood cells, hexokinase can phosphorylate fructose to the glycolytic intermediate fmctose 6-phosphate (F6P). 

Within the MTR model, the effect of trapping can be described using two approaches. In the first approach, one can assume that all carriers field induced above... 

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