High resistance sample

In Section 1 we will use the theory developed in Appendix A to discuss the various measurement and analysis techniques that have been applied to SI GaAs. We will also discuss the precautions that must be observed in apparatus design, and present an automated Hall-effect and photo-electronic system capable of measuring high resistivity samples. 

Other common means for determining the direct d33 coefficients of bulk samples include Berlincourtstyle approaches. Berlincourt meters are available commercially from several sources. In most cases, the sample to be measured is mechanically clamped between jaws with pressures on the order of a few N. The charge output due to a small mechanical oscillation (forces 0.1-0.3N) is then determined. It is important to note that this technique is appropriate for measurements of bulk samples with stable domain states, only. Measurement accuracy is also better when highly resistive samples are used. 

Polarization of O-2 High resistivity sample re- Low resistivity sample with... 

High resistivity sample strong inter- Low resistivity sample weak interaction action between R-OH and the surface between R-OH and surface (e) trapped... 

In high resistivity samples, the absorption edge was relatively sharp it corresponded to an energy gap of 1.02 eV which is close to the 1.04 eV energy gap value reported in the literature for CuInSe2 single crystals. 

Some samples were subsequently annealed for periods between 0.5 to 1 hour in vacuo or in hydrogen at 400°C. The resistivity of these samples usually increased, and sometimes a change from p- to n-type conductivity was observed. Such short heat-treatments didn t affect either structural or optical properties of the films. Some other samples were buried in CuInSe2 crystalline powder, sealed in an evacuated quartz ampoule and annealed for a long period (about 16 hours) at 500°C. Low resistivity samples retained their low resistivity, and the resistivity of high resistivity samples slightly increased, but no conversion to n-type conductivity was observed. 

This specification is an indication of the ability of the meter to handle high resistance samples or electrodes, without significant noise or error. The test consists of comparing identical millivolt inputs with and without a high resistance in the circuit. Proceed as follows ... 

Adding a neutral salt to the sample is one procedure for reducing error in a high resistance sample. As previously discussed, this changes the ionic strength slightly and therefore the hydrogen ion... 

When a conventional 2-probe measurement instrument such as an ohmmeter is sought to be applied to a highly resistive sample, the contact resistance between the probe and the sample constitutes a major impediment. To circumvent this, 4-probe techniques, such as those illustrated in Fig. 11-1 are used. In these, a current is applied between the outer probes, and the voltage differential between the inner probes is measured. Such techniques were proposed by van der Pauw, among others [386]. 

The maximum value for the tortousity was 30 and the value for the tortusity of each sample was estimated from the formation factor. The formation factor was taken either from resistivity measurents or estimated from NMR measurements and the Myers pore-combination model [37]. A comparison of the estimated permeability correlations is given in Figure 3.6.9. The SDR model overestimates the permeability of low permeability samples and the Chang model underestimates the permeability of high permeability samples. The modified Chang model, Eq. (3.6.9), improves the estimate of permeability for both low and high permeability samples. 

Essentially identical profiles seem to be observed for high-resistivity n-and p-type samples deuterated under the same conditions. This is to be expected if the samples are instrinsic in all cases (donor or acceptor concentration < 2 x 1013 cm-3 at 150°C, or < 2 x 1015 cm 3 at 300°C),... 

InPrZn is shown in Fig. 8. In the neutralized region, the sample is highly resistive (>105 fl.cm). High resistivity has also been reported in the case of hydrogenated GaAs C (Pan et al., 1987b) and p-type InP Mn (Omel yanovskii et al., 1989). 

In the study, five FRC samples, about 3 to 5 mm in thickness, were examined. The results from the study show that FRC materials have high resistance to ignition, high heat of gasification and high resistance to self-sustained fire propagation. These results suggest that a composite combat vehicle, by virtue of its construction, does not present an unusual fire hazard. 

Figure 19. Transmission of high-resistivity silicon in the range beyond 20 microns. The samples are uncoated.

Beller and Simoneit [20] studied the occurrence of hexachlorophene in extracts of estuarine sediments taken from the Hudson River. Hexachlorophene was detected only in the humic acid fractions of the samples, indicating that it could bind strongly to organic matter and was highly resistant to degradation in that form. 

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