Capacitance experimental materials

From experimental measurements it was found that there was a fairly good linear relation between the SC capacitance and current, the slope being dependent on the electrode material and electrolyte. If the dependence is known, it can be used to make the Ragone plot calculations more accurate. Therefore, the following method was employed in our evaluations. 

Group 14 (IV) elements as, 22 232 high throughput experimentation, 7 382t, 414t hydrides in, 13 609 introduction of dopants into, 14 428 ion dose for, 14 427 photon interaction with, 23 33—34 as photosensitive materials, 22 716 scanning capacitance microscopy,... 

The monotonic increase of immobilized material vith the number of deposition cycles in the LbL technique is vhat allo vs control over film thickness on the nanometric scale. Eilm growth in LbL has been very well characterized by several complementary experimental techniques such as UV-visible spectroscopy [66, 67], quartz crystal microbalance (QCM) [68-70], X-ray [63] and neutron reflectometry [3], Fourier transform infrared spectroscopy (ETIR) [71], ellipsometry [68-70], cyclic voltammetry (CV) [67, 72], electrochemical impedance spectroscopy (EIS) [73], -potential [74] and so on. The complement of these techniques can be appreciated, for example, in the integrated charge in cyclic voltammetry experiments or the redox capacitance in EIS for redox PEMs The charge or redox capacitance is not necessarily that expected for the complete oxidation/reduction of all the redox-active groups that can be estimated by other techniques because of the experimental timescale and charge-transport limitations. 

We now discuss some of the experimental aspects of temperature spectroscopy. Lang (1974) called his original method deep level transient spectroscopy (DLTS), and he measured capacitance transients produced by voltage pulses in diodes made from conductive materials. However, in SI materials, this method is not feasible and an alternate method, involving current transients produced by light pulses in bulk material (or Schottky structures), was... 

After an overview over the experimental techniques and results from the literature (Sect. 7.2) and some words about technical aspects and our experience concerning problems with some materials (Sect. 7.3), the experiments of the authors can be outlined as follows first, measurements of ohmic and capacitive currents in the contact mode are described (Sect. 7.4), followed by a description of some surface charge measurements in the non-contact mode (Sect. 7.5). The chapter closes with some experiments to probe electro-mechanical properties by the use of piezo response microscopy (Sect. 7.6) with its own brief literature overview. All three experimental parts are opened by a short introduction to the SFM techniques implemented in our lab. 

It is well known that experimental CVs for species in solution phase frequently diverge from theoretical ones for -electron reversible couples. The divergence can be caused by a variety of factors deviations from reversibility, occurrence of coupled chemical reactions and/or surface effects, and resistive and capacitive effects (Nicholson and Shain, 1964 Nicholson, 1965a). These last effects will be briefly treated here because of their potential significance when microheterogenous deposits or more or less homogeneous coatings of microporous materials cover the electrode surface. 

Hesslacher first suggested the possible use of nickel oxide as a positive material in alkaline cells. The experimental techniques have been mainly based on the measurements of current, voltage, resistance and capacitance. 

The experimental results discussed in this section were obtained from measurements on solar-cell-grade material deposited from low-power rf (13.56-MHz) plasma-assisted CVD of pure silane at 30 mTorr, wiffi a high flow rate, on substrates held at 250 C on the anode of a capacitive-geometry reactor. These deposition conditions are fairly typical for preparation of high-quality films. 

Impedance spectroscopy has shown us that there is accumulation of the material s charge carriers near the electrodes. Furthermore, experimental conditions, specifically temperature and the gaseous environment, seem to have only a very limited influence upon the capacitive effect resulting from this charge accumulation. 

---