Activation energy conductivity

Table 3 summarizes some of the present state-of-the-art parameters obtained for undoped and doped i -SiH(F) material thus produced. The device-quahty material exhibits semiconductivity because In G vs 10 /Texhibits a straight line with a conductivity activation energy of eV, which is... 

Fig. 3. The room temperature dark conductivity, (Hem), and conductivity activation energy, AH in eV, plotted as A, a function of vppm of AsH ( ) B, PH (a) and C, B2H ( ) into the premix gas ratio of Sip4 H2 = 10 1. Thepton transition (left to right) refers to i -Si F H alloy, and D refers to doping...

The low DOS achieved in i -Si H enables it to be readily doped, a prerequisite for any device appHcation n- and -type doping is achieved by the addition of PH and B2H to SiH in the gas phase, respectively. Figure 3, a plot of and conductivity activation energy, AH, as a function of PH and 2 6 content, shows that the most heavily f -type doping results in (Hem). By manipulating the plasma (using SiF and H2) or heavily diluting... 

Table 53. Molar conductivity (p, cm2ohm mot1) and conductivity activation energy (U of molten systems KF - K2TaF7 and KCl - K2TaF7. Reproduced from [324], A. I. Agulyansky, P. T. Stangrit, V. I. Konstantinov, Zh. Prikl. Khim. 51 (1978) 2720, Copyright 1978, with permission of Nauka (Russian Academy of Sciences) publishing.

FIG. 39. Electrical conductivity activation energy vs nitrogen content. (Reproduced from [14].)... 

Figure 2.3 Dielectric relaxation maximum as a function of DC conductivity activation energy E .

The dielectric constant e can be estimated to be of the order of 100, and the donor concentration N can be estimated from the measured conductivity, activation energy.and Hall mobility to be of the order of 10 cm. Then W = 10 cm and L is even smaller, so that expansion of the exponential yielSs a quantum efficiency porportional to the optical absorption coefficient even for large values of a. 

The DC conductivity of single crystals and the pressed powder of the synthesized salts has been measured in the temperature range of 77-300 K by four-contact technique. Table 1 presents the values of specific electrical conductivity at room temperature aRT and of conductivity activation energy A calculated on the basis of resistive measurements at various temperatures. Conductivity models applied for the calculation of the A value in each compound are presented and discussed in the next section. 

Tablet. Properties of anion-radical salts of TCNQ andMTCNQ vmin beginning of the continuos absorption in IR spectrum A - the values of conductivity activation energy obtained from the data of resistive measurements aRT - specific conductivity at room temperature.

For all the studied compounds, values of conductivity activation energy A calculated from the data of resistive measurements (Table 1) exceed those estimated in the analysis of IR absorption spectra. This difference may be due to the quality of crystals and to that of the electric contacts used for conductivity measurements. 

The comparable equilibrium behavior of p-type a-Si H films is shown in Fig. 6.7. The density of band tail holes, has a smaller activation energy than the n-type material and is constant at the highest doping levels. The increase in conductivity activation energy at the equilibration temperature is less obvious than in the n-type material (see Fig. 5.2), but the frozen state is identified by the dependence on thermal history. The equilibration temperature is lower than in n-type material by about 50 °C and the relaxation times in Fig. 6.5 are also correspondingly shorter. 

Fig. 7.2. Schematic diagram of the density of states distribution showing the conductivity activation energy, the average conduction energy, with respect to the mobility edges, and the Fermi energy. The temperature dependence parameters, 7j., and are indicated.

Fig. 7.3. Measured values of the conductivity prefactor a, versus the conductivity activation energy, showing the Meyer-Neldel relation. Data from sever different laboratories are shown (Tanielian 1982).

Therefore, within the linear approximation, the conductivity activation energy Eg measures the value of ( tr— )g and the prefactor contains the additional factor exp(y/k). The temperature dependence of the energies accounts for the Meyer-Neldel relation provided that... 

Fig. 7.6. Plot of the conductivity activation energy and prefactor and the dangling bond density at different stages of annealing of electron-bombarded a-Si H (Stuke 1987).

Table 2 Electronic conductivity, activation energy, and optical threshold. Eg, of pristine polyaer.

The d.c. conductivity activation energy is often designated as E , Eq, E, Ejc and (0) in the literature and all are equivalent. We have used Ej as preferred description in this book although in chapter 6, has been used to make it known that it is an activation barrier. But otherwise represents the primitive activation barrier observed in a.c. measurements. 

Figure 8.29. Substitutional doping in glow discharge a-Si H (a) Changes in room temperature d.c. conductivity by doping with P and B. Intrinsic region is marked as defect-controlled (b) d.c. conductivity activation energy AEg (= E,/ ) is shown for the dopants (After Spear and Le Comber 1976).

For most ionic conductors, the conductivity activation energy ( ) may be consid-... 

Fig. 1. Properties of chromia-alumina catalysts O, activity for conversion of heptane to toluene X, activity for conversion of methylcyclohexane to toluene , activation energy for conduction activation energy for heptane conversion.

In this paper, we compare experimental data on morphology of the vacuum deposited PTCDI films and their electrical conduction. As known [2], the conduction of PTCDI films is strongly influenced by adsorption of the atmospheric oxygen. Therefore, the measured absorbed oxygen concentration dependencies of conductivity, activation energy and turmel faetor are represented and then conqjared with the theoretical calculations based on the two-level model of the hopping conductivity [3]. 

The measured dependencies of the conductivity, activation energy and tunnel factor on the concentration of adsorbed oxygen show that the hopping mechanism is realized in nanostructured PTCDI films. The main features of the electrical properties can be explained by means of Fig. 2, where x is the ratio of the adsorbed oxygen concentration to the full concentration of localization centers in the material. Lines A-A and B-B show the theoretical values for intrinsic and impurity... 

Figure 2. The dependence of conductivity activation energy on the relative concentration of adsorbed oxygen molecules.

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