Microwave Hall Research Articles

Microwave Hall mobility measurements on rat liver mitochondria and spinach chloroplasts

The effect of known respiratory inhibitors on the charge carrier hall mobility of rat liver mitochondria has been investigated using a microwave technique. Potassium cyanide and rotenone were found to reduce the Hall mobility, but no effect was observed for antimycin-A. The marked effect of potassium cyanide and the low mobility value obtained for the lipid extract of the mitochondria, suggest that electronic conduction through the electron transport chain is being observed. Volume-corrected values of between 50 and 80 cm2/V sec are found for the electron Hall mobility. Measurements on spinach chloroplasts give P-type Hall mobility values of 0·5 and 0·8 cm2/V sec.

Microwave dielectric and Hall effect measurements on biological materials.

A technique for the measurement of the Hall effect Faraday-type rotation at microwave frequencies is described. The essential features of this electrodeless technique are the employment of a bimodal resonating cavity and the fact that intra- and inter-crystalline defects can be ignored. A new approach of possible significance for measurements on hydrated biological materials is proposed, by which the perturbations of a resonating cavity on insertion of a thin, small dielectric specimen may be formulated to include perturbations higher than the first order. The theory of the Hall effect Faraday-type rotation relevant to biological materials, where the effect of displacement currents associated with loosely bound water must be included, is outlined. Hall mobility results are given for some biomacromolecules, rat liver mitochondria and spinach chloroplasts.

Factors affecting conduction in polymeric complex TCNQ salts

Conductivity measurements are reported on both isotactic and atactic polyvinyl pyridinium complex TCNQ salts. The isotactic materials are significantly better conductors than those derived from atactic materials, but not as good as those derived from the monomeric base. Seebeck and microwave Hall mobility measurements indicate that the isotactic materials behave as polycrystalline complex radical salts, whereas the atactic materials exhibit behaviour consistent with hopping conduction.

Crossed-guide Method for the Measurement of Microwave Hall Mobility†

ABSTRACT The microwave Hall mobility of an n-type silicon sample has been measured for magnetic fields up to 5 kilogauss by a crossed -guide technique previously suggested by the authors. The experimental results at a frequency of 9·48 Ges are found to agree closely with the expected values. The possible sources of experimental error are also discussed.

On a Method for Measurement of Microwave Hall Mobility of Semiconductors†

ABSTRACT The formula giving the absolute value of microwave Hall mobility in terms of the measured parameters in Hambleton and Gartner's method is derived. It is shown that it is not possible to determine the absolute value of Hall mobility by this method. A modification of the method which eliminates this limitation is suggested.

High-Field Study of a Hall-Effect Microwave Converter

Utilization of the Hall effect in the frequency conversion of microwaves with gain was investigated. A conversion gain which seemed to be feasible was found to be dependent on the control sensitivity of the conversion system. A high control sensitivity can be achieved through use of a high-mobility Hall sample, like InSb, an efficient coupling of a modulating field to the sample, and a suitable high-energy pump source. The high-power test was performed by using a pulsed microwave pump. Conversion gains were measured as a function of the pumping power and showed some ``saturation'' effects. These effects were explored and explained, based on the behavior of carriers in the sample under high-power microwave fields. In particular, a breakdown field beyond which the saturation seemed to disappear was found. The present S band experimental model still suffered a conversion loss of 25 to 30 dB. Results have, however, revealed the possibility of a practical microwave Hall converter with gain.

Microwave Hall effect and the accompanying rotation of the plane of polarization

Faraday rotation of the plane of polarization of an electromagnetic wave, propagated through a medium in the direction of an independently applied steady magnetic field, has been interpreted in terms of gyromagnetic action and in certain circumstances as a consequence of Hall effect.The paper calls particular attention to the Hall-effect mechanism, which is shown to lead to different propagation coefficients for the right-handed and left-handed circularly-polarized components of a plane wave.The contention is advanced that a Hall effect can be expected to arise from a displacement current in the material medium and that, as a consequence, the Faraday rotation effect in dielectrics and semiconductors may, in some cases, be significantly modified at frequencies above the microwave part of the spectrum. Some elementary calculations are given in support of this argument.

Electrical Structure of PbS Films

The electrical properties of chemically deposited lead sulfide films have been investigated as a function of frequency from dc into the microwave range. Conductivity and Hall mobility measurements have been made on both the dark and the photoexcited carriers. The dark conductivity is independent of frequency below 100 Mc/sec. It increases by almost an order of magnitude over a decade in frequency and then becomes constant again at higher frequencies. This behavior is typical of a material whose low-frequency conductivity is limited by barriers. Surprisingly the photoconductivity behaves quite differently. The photoconductivity has a hump around 100 Mc/sec but otherwise is relatively independent of frequency. The Hall mobilities of the dark and photocarriers are equal at dc in agreement with earlier studies. Microwave Hall measurements indicate that the dark carriers have about the same apparent mobility at 10 kMc/sec as at dc. It is shown that the conventional barrier model with a photoinduced change in carrier concentration cannot account for the behavior of these films. Nor can a model in which the barrier height is modified by illumination. The present studies suggest that there are connecting channels through the films and that the photoresponse of the films is determined by the behavior of these channels. A simple model is constructed and its parameters are adjusted to fit the conductivity data and the dc Hall mobility. As a check on the model the measured microwave Hall mobility is compared with the predicted value. Good agreement is found for high-quality commercial films. The hump observed in the photoconductivity follows naturally from this model, being associated with a modulation of the barrier capacitance. Studies of the photoconductive decay yield the same time constant at dc and microwave frequencies, supporting the picture that the same photocarriers are responsible for the dc and microwave photoconductivity.

Microwave Hall effect in germanium and silicon at 20 kmc/s

Microwave Hall effect in germanium and silicon at 20 kmc/s