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Free electron concentration

For depth inhomogeneities in the free electron concentration n x) and electron mobility the Hall-effect measurement yields an effective... [Pg.133]

An example of the temperature dependence of donor neutralization is shown in Fig. 3. Devices with a square van der Pauw geometry were exposed to H° for 30 min. at different temperatures. Hydrogenation reduces the free-electron concentration over the entire investigated temperature range, with a maximum reduction of approximately 40% at 140°C. In... [Pg.134]

Fio. 3. Dependence on hydrogenation temperature of the free-electron concentration (a) and the electron Hall mobility (b) in phosphorus-implanted n-type silicon (Johnson et al., 1987c). [Pg.135]

The diffusion of hydrogen in highly or lightly silicon doped GaAs induces a modification of the electrical properties of the material a reduction of the free electron concentration (Fig. 2) and a significant increase of the electron mobility up to values close to the mobility in nonhydrogenated materials with the same net carrier concentration (Jalil et al., 1986 Pan... [Pg.466]

Figure 7.1 shows the optical transmission and reflectance spectra of the two films. The main difference is an increase in the mid-IR reflectance of the doped film compared with the undoped one, due to the high free electron concentration... [Pg.267]

Before discussing photoconductivity in more detail it should be noted that absorption measurements themselves can be quite useful. From Eq. (36a) it is seen that if the cvni are known and if a can be measured, then the nw can be determined. Further, if the , are known (or can be measured) and the equilibrium free-electron concentration n0 is measured (giving EF), then the Nt can also be determined from Eq. (Bile). Usually a is calculated from a transmission measurement i.e.,... [Pg.99]

Fig. 9. The behavior of the occupied trap concentration n, [Eq. (63)] and the free electron concentration n [Eq. (65)] during and after a light pulse of duration tp. For part (a) the parameters are eni = 0.6ms-1, / = 1.2 ms-1, and x"1 = 11.8 ms"1. For part (b) the parameters are e.i = 0.06, 0.6, and 6 ms"1, respectively, for curves (i), (ii), and (iii). The choice of parameters is for illustrative purposes only and may not reflect a realistic situation. The shape of n, is only approximately correct in the dotted portions. Part (c) shows the gating functions for boxcar and lock-in amplifiers, respectively. Fig. 9. The behavior of the occupied trap concentration n, [Eq. (63)] and the free electron concentration n [Eq. (65)] during and after a light pulse of duration tp. For part (a) the parameters are eni = 0.6ms-1, / = 1.2 ms-1, and x"1 = 11.8 ms"1. For part (b) the parameters are e.i = 0.06, 0.6, and 6 ms"1, respectively, for curves (i), (ii), and (iii). The choice of parameters is for illustrative purposes only and may not reflect a realistic situation. The shape of n, is only approximately correct in the dotted portions. Part (c) shows the gating functions for boxcar and lock-in amplifiers, respectively.
Extending the definition of n-type and p-type reactions, as defined by Vol kenshtein (21) to the electron transfer step, it would seem that the only reaction given by Equation 1 is a p-type reaction. This reaction would be accelerated by the increase in the value of free hole concentration. On the other hand, all other reactions besides the one given by Equation 1 are n-type and would be accelerated by the increase in free electron concentration. Hydrocarbon oxidation reactions catalyzed by solid oxides are accompanied by oxidation and reduction of the catalyst and the degree of the stoichiometric disturbance in the semiconductor changes. The catalytic process in the oxidation of 2-methylpropene over copper oxide catalyst in the presence of Se02 can be visualized as ... [Pg.285]

There was no evidence for free electrons, and it was concluded that the free-electron concentration must have been less than 3 x 108 electrons/ cm3. [Pg.140]

Let us turn now to the other conclusions which can be based on free electron theory. The Hall effect measurements of Kyser and Thompson permitted the computation of the free electron concentration. The Hall effect is produced by a balance between the magnetic force (Lorentz force) on a current carrier and the electric force produced by a displaced charge density within a conductor. For a charge, q, moving... [Pg.108]

GaN, relaxed homoepitaxial layers, Mg-doped bulk (low free-electron concentration) 3.1885 0.0003 5.1850 0.0001 [6]... [Pg.10]

Thermal expansion of a semiconductor depends on its microstructure, i.e. stoichiometry, presence of extended defects, ffee-carrier concentration. For GaAs [24] it was shown that for samples of free-electron concentrations of about 1019 cm"3, the thermal expansion coefficient (TEC) is bigger by about 10% with respect to the semi-insulating samples. Different microstructures of samples examined in various laboratories result in a large scatter of published data even for such well known semiconductors as GaP or GaAs. For group III nitrides, compounds which have been much less examined, the situation is most probably similar, and therefore the TECs shown below should not be treated as universal values for all kinds of nitride samples. It is especially important for interpretation of thermal strains (see Datareview A 1.2) for heteroepitaxial GaN layers on sapphire and SiC. [Pg.29]

I) bulk crystal (grown at high pressure) of a high free electron concentration (5 x 1019 cm"3) ... [Pg.29]

II) slightly strained homoepitaxial layer of a small free electron concentration (about 1017 cm 3) on highly conductive GaN substrates ... [Pg.29]

Note that sample I with a high free-electron concentration has a thermal expansion higher by about 3% with respect to the homoepitaxial layer II (this value could be measured with a high accuracy because the separation of Bragg peaks from the substrate and the layer was used). In the case of the heteroepitaxial layer, the thermal expansion of the substrate induces different thermal expansion of the layer and creation of thermal strain (it varies from sample to sample see Datareview A1.2). [Pg.30]

Zhang et al [27] reported on the decrease of the 00.2 FWHM for decreasing free-electron concentration in their MOVPE GaN layers on sapphire. For free-electron concentration of about 1016 cm 3, the 00.2 FWHM was less than 7 arc min, whereas it was about 11 arc min for a concentration of 1020 cm 3. Similarly, Lee et al [22] found an increase of mosaicity (10.5 reflection) versus free-electron concentration for Si-doped GaN layers. [Pg.260]


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