Atomic and Nuclear Physics

Biography

Biography: Igor Vladimirovich Malyshev

Abstract

With the extension of the upper extreme high frequency (EHF) range limit upper volume of modern radio engineering devices to the terahertz range, developers are faced with the possibility of taking into account the peculiarities of the physical processes occurring in the semiconductor structures bulks for constructing of new type converter devices. The chips of these devices are capable in their work to be exposed to strong external electric (EF) and magnetic (MF) fi elds with high intensities. Such conditions are created in the bulks of modern semiconductor structures and super lattices made of AIIIBV type materials operating in the mentioned range and usually do not take into account the volume diff usion nonlinearities, which as shown in a number of works, contribute signifi cantly to the output current density. So recently, it has been proved that under conditions of external electric fi eld intensities approaching and exceeding the threshold value of the Gunn eff ect (about 4 kV /cm), the diff usion component of the output current will be commensurable with the drift current. Th is account is made on the basis of the phenomenological representation of the processes of averaged drift and heating and considering the dependence of the eff ective mass (m) on the energy (W) represented by the Taylor series expansion result. Th e relaxation times of the quasimomentum (τ) and the energy (τe) were assumed to be independent of the charge carriers energy. It was found that the diff usion nonlinear components should be taken into account when calculating the output parameters of mixers, multipliers and self-excited generators using hot electrons in the mentioned frequency ranges. As a result of theoretical calculations, the amplitude dependences of the constant (D0) and variable (D~) diff usion coeffi cients were found, which can be defi ned as the "bulk diff usion detection eff ect" and that undoubtedly, is a poorly understood phenomenon. Also mutually orthogonal effects of electric and magnetic fi elds on the processes of carrier drift and diff usion are considered. It was found that the main electro physical parameters, due to the action of the Lorentz force, acquire a vector-component form along the x and y axes of the Cartesian coordinate system. In addition, a number of new eff ects on drift and diff usion characteristics have been discovered. Thus, it was found that the components of the drift velocity and the diff usion coeffi cient along the longitudinal (x-axis) of the main drift direction are independent of the transverse magnetic fi eld but are determined only by the longitudinal EF along this direction and the transverse (y-axis) component of the drift velocity for strong magnetic induction values (Bz > 4.0 T) demonstrates the displacement of the falling section beginning on the drift (volt-ampere) characteristic in the direction of decreasing (by a factor of 2), which probably indicates a new "Gunn eff ect controlled by a magnetic fi eld". Reducing the intensity of the threshold fi eld of the Gunn eff ect from 4 to 2 kV / cm will allow to increase the effi ciency of the bulk diode by 50% (assuming the output current density and load conductivity remains unchanged). Th us, the fundamental possibility of creating two-dimensional devices for frequency conversion (autodyne type mixers) has been revealed. In addition, in the case of realizing the possibility of magnetic fi eld modulation (or manipulation according to a given function), it becomes possible to obtain the pulse-modulated (or manipulated) microwave or EHF oscillations. For obtained analytical experimental verifi cation results a semiconductor structure sample construction and the experimental setup structural image are proposed.