Effect of Lanthanum Substrates on the Structural, Optical and Electrical Properties of Copper Selenide Thin Films Designed for 5G Technologies

In this work, copper selenide thin films coated onto glass and transparent lanthanum substrates are studied. The (glass, La)/CuSe thin films which are prepared by the thermal evaporation technique under a vacuum pressure of 10− 5 mbar are structurally, morphologically, optically, dielectrically and electrically characterized. Lanthanum substrates improved the crystallinity by increasing the crystallite size and decreasing both of the microstrains and defect density of copper selenide. La substrates redshifts the energy band gap and doubled the dielectric constant values. In addition, employing Drude-Lorentz approaches for optical conduction to fit the dielectric constant provided information about the effects of La substrates on the drift mobility, plasmon frequency, free carrier density and scattering times at femtosecond level. The drift mobility increased and the plasmon frequency range is modified when La substrates are used. Verifying impedance spectroscopy test in the microwave frequency domain have shown that the La(gate)/CuSe/Ag (source) transistors can be employed as band pass filter suitable for 5G technologies. The microwave cutoff frequency reached ~ 5.0 GHz at a notch frequency of 2.80 GHz of the La/CuSe/Ag highpass filters.

Accurate Electron Drift Mobility Measurements in Moderately Dense Helium Gas at Several Temperatures

We report new accurate measurements of the drift mobility μ of quasifree electrons in moderately dense helium gas in the temperature range 26K≤T≤300K for densities lower than those at which states of electrons localized in bubbles appear. By heuristically including multiple-scattering effects into classical kinetic formulas, as previously done for neon and argon, an excellent description of the field E, density N, and temperature T dependence of μ is obtained. Moreover, the experimental evidence suggests that the strong decrease of the zero-field density-normalized mobility μ0N with increasing N from the low up to intermediate density regime is mainly due to weak localization of electrons caused by the intrinsic disorder of the system, whereas the further decrease of μ0N for even larger N is due to electron self-trapping in cavities. We suggest that a distinction between weakly localized and electron bubble states can be done by inspecting the behavior of μ0N as a function of N at intermediate densities.

Investigation of Photoexcitation Energy Impact on Electron Mobility in Single Crystalline CdTe

The exceptional electronic properties of cadmium telluride (CdTe) allow the material to be used in a wide range of high energy radiation detection applications. Understanding the mechanisms of local carrier scattering is of fundamental importance to understand the charge transport in the material. Here, we investigate the effect of photoexcitation on electron transport properties in chlorine doped single crystalline cadmium telluride (SC-CdTe:Cl). For this purpose time of flight measurements were performed on SC-CdTe:Cl in order to study the electron drift mobility in the low injection regime. Measurements were made at the temperature intervals of 80 to 300 K, for an applied electric field between 270 and 1600 V/cm and for wavelengths of 532, 355 and 213 nm. We have found that the electron drift mobility was affected by the excitation energy for temperatures below 200 K. In addition, the measurements revealed that it is possible to determine impurity and shallow trap concentration by this method. The method proves to be extremely sensitive in measuring very low impurity levels and in identifying dominant scattering mechanisms.

Summary of New Insight into Electron Transport in Metals

This paper gives a summary of a new insight into basic electron transport characteristics in crystalline elemental metals. The general expressions based on the Fermi-Dirac distribution of the effective density of the randomly moving electrons, their diffusion coefficient, drift mobility, and other characteristics, including the Einstein relation between diffusion coefficient and drift mobility, are presented. It is shown that the creation of the randomly moving electrons due to lattice atom vibrations produces the same number of electronic defects, which cause scattering of the randomly moving electrons and related transport characteristics.

I─V characteristics of Bi4Ge3O12─Mn crystals in the unipolar injection mode

Current-voltage relations in Bi4Ge3O12 ─ Mn crystals were measured under the conditions of unipolar injection of charge carriers. The characteristics obtained for electrons and holes are different. I-V curves in the case of electron injection contain ohmic, quadratic regions and regions of a sharp increase in current. This indicates the formation of a space charge enriched in electrons. The values of conductivity, effective drift mobility, and electron concentration calculated at different temperatures are close to the values obtained for pure crystals. In the case of hole injection I-V curves are characterized by the presence of sublinear regions. It is assumed that injection of the holes causes the formation of a space charge layer depleted in electrons due to the recombination. It is shown that doping with manganese does not change the nature of conductivity in bismuth germanate crystals and strongly affects the recombination processes.

Analysis of a Passive Memristor Crossbar

The purpose of the present research is to propose a detailed analysis of a fragment of a passive memristor memory crossbar. For computer simulations a previously proposed by the authors in another paper nonlinear dopant drift memristor model with a modified window function is now applied. The results obtained by the simulation are compared with experimentally recorded current-voltage relationships and with these derived by the use of several basic memristor models as well. A relatively good coincidence between the results is established. The fragment of a memristor memory crossbar is simulated for the procedures of writing, reading and erasing information in the memristor cells. The effect of the basic memristor parameters, as the ionic drift mobility, the ON and OFF resistances and the physical length of the element on its switching speed is discussed. After a number of simulations, it was established that due to the self-rectifying effect the parasitic sneak paths do not strongly influence the normal operation of the memristor memory crossbar. It is confirmed that the model with a modified Biolek window function proposed in our previous research could be used for simulations of complex memristive electronic circuits for hard-switching.