Dielectric analysis advantages

In quadrupole-based SIMS instruments, mass separation is achieved by passing the secondary ions down a path surrounded by four rods excited with various AC and DC voltages. Different sets of AC and DC conditions are used to direct the flight path of the selected secondary ions into the detector. The primary advantage of this kind of spectrometer is the high speed at which they can switch from peak to peak and their ability to perform analysis of dielectric thin films and bulk insulators. The ability of the quadrupole to switch rapidly between mass peaks enables acquisition of depth profiles with more data points per depth, which improves depth resolution. Additionally, most quadrupole-based SIMS instruments are equipped with enhanced vacuum systems, reducing the detrimental contribution of residual atmospheric species to the mass spectrum. 

Dielectric spectroscopy, also known as impedance spectroscopy, has been used for process analysis for some time, as it offers the ability to measure bulk physical properties of materials. It is advantageous to other spectroscopic techniques in that it is not an optical spectroscopy and is a noncontact technique, allowing for measurement without disturbing a sample or process. The penetration depth of dielectric spectroscopy can be adjusted by changing the separation between the sensor electrodes, enabling measurement through other materials to reach the substrate of interest. Because it measures the dielectric properties of materials, it can provide information not attainable from vibrational spectroscopy. 

It is known that in some cases the modulus representation M (oo) of dielectric data is more efficient for dc-conductivity analysis, since it changes the power law behavior of the dc-conductivity into a clearly defined peak [134]. However, there is no significant advantage of the modulus representation when the relaxation process peak overlaps the conductivity peak. Moreover, the shape and position of the relaxation peak will then depend on the conductivity. In such a situation, the real component of the modulus, containing the dc-conductivity as an integral part, does not help to distinguish between different relaxation processes. 

An advantageous analysis of electrical conductivity relaxation is undertaken in the complex modulus formalism [150] adapted for analysis of dielectric processes occurring in materials with large concentrations of mobile charge carriers, such as inorganic salts [151] and composite polymeric systems [152], that suppress the influence of electrode polarization, allowing the determination of d.c. conductivity. 

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