In this short review some aspects of applications of free electron theory on the ground of the Fermi statistics will be analyzed. There it is an intention to attempt somebody’s attention to problems in widespread literature of interpretation of conductivity of metals, superconductor in the normal state and semiconductors with degenerated electron gas. In literature there are many cases when to these materials the classical statistics is applied. It is well known that the electron heat capacity and thermal noise (and as a consequence the electrical conductivity) are determined by randomly moving electrons, which energy is close to the Fermi energy level, and the other part of electrons, which energy is well below the Fermi level can not be scattered and change its energy. Therefore there was tried as simple as possible on the ground of Fermi distribution, and on random motion of charge carriers, and on the well known experimental results to take general expressions for various kinetic parameters which are applicable for materials both without and with degenerated electron gas. It is shown, that drift mobility of randomly moving charge carriers, depending on the degree degeneracy, can considerably exceed the Hall mobility. Also it is shown that the Einstein relation between the diffusion coefficient and the drift mobility of charge carriers is valid even in the case of degeneracy. There also will be presented the main kinetic parameter values for different metals.

This report deals with a 1/f noise in homogeneous classical semiconductor samples on the base of silicon. We perform detail calculations of resistance fluctuations of the silicon sample due to both a) the charge carrier number changes due to their capture–emission processes, and b) due to screening effect of those negative charged centers, and show that proportionality of noise level to square mobility appears as a presentation parameter, but not due to mobility fluctuations. The obtained calculation results explain well the observed experimental results of 1/f noise in Si, Ge, GaAs and exclude the mobility fluctuations as the nature of 1/f noise in these materials and their devices. It is also shown how from the experimental 1/f noise results to find the effective number of defects responsible for this noise in the measured frequency range.

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We present a 24×24 pixel camera capable of high-speed THz imaging in power-detection mode. Each pixel of the sensor array consists of a pair of 150-nm NMOS transistors coupled to a patch antenna with resonance at 600 GHz. The camera can operate with a speed of up to 450 frames per second where it exhibits a minimum resolvable power of 10.5 nW per pixel. For a 30-Hz frame rate, the minimum resolvable power is 1.4 nW.

A detail analysis of electrical and optical fluctuations of large power (1 W) green light-emitting diodes (LEDs) is presented. Special attention was directed to measurement and interpretation of correlation coefficient between electrical and optical fluctuations. The correlation coefficient was measured not only over frequency range from 10 Hz to 20 kHz, but also in every one-octave frequency band by using digital filters. It is shown that correlated part of electrical and optical fluctuations for investigated green LEDs is related with random potential fluctuations of parameters of quantum well due to charge carrier capture by the defects in the active layer, while uncorrelated part of electrical noise is caused by parallel leakage channel which resistance is many times higher than that of p-n junction.

Interpretation of the conductivity of metals, of superconductors in the normal state and of semiconductors with highly degenerate electron gas remains a significant issue if consideration is based on the classical statistics. This study is addressed to the characterization of the effective density of randomly moving electrons and to the evaluation of carrier diffusion coefficient, mobility, and other parameters by generalization of the widely published experimental results. The generalized expressions have been derived for various kinetic parameters attributed to the non-degenerate and degenerate electron gas, by analyzing a random motion of the single type carriers in homogeneous materials. The values of the most important kinetic parameters for different metals are also systematized and discussed. It has been proved that Einstein's relation between the diffusion coefficient and the drift mobility of electrons is held for any level of degeneracy if the effective density of randomly moving carriers is properly taken into account.

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