| Authors |
Grunin Aleksandr Borisovich, Doctor of physical and mathematical sciences, professor, sub-department
of physics, Penza State University (40 Krasnaya street, Penza, Russia), grunin.sky@uandex.ru
Kirillov Il'ya Andreevich, Postgraduate student, Penza State University (40 Krasnaya street, Penza, Russia), kirillov.ia1990@yandex.ru
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| Abstract |
Background. The development of semiconductor nanoelectronics is determined by the creation of new devices based on low-dimensional structures with desired electronic spectrums - quantum dots (QD), quantum wells (QW), quantum wires (QWire), quantum cylinder (QC) superlattices (SL), etc. A feature of these structures is the ability to control their transport and optical properties in external fields. In addition, the optical and electrical properties of semiconductor low-dimensional structures are largely determined by the presence of impurities. As of today, an especially actual task of nanoelectronics is to investigate the influence of strong external fields on the transport properties of semiconductor low-dimensional systems with impurity centers, since, for example, the influence of a strong electric field may lead to ionization of impurities, and, therefore, to changes of the concentration of free charge carriers in the conductivity region [1]. The aim of this work is to theoretically study the influence of an external electric field on the binding energy of the quasistationary impurity states in QWire in conditions of thermoelectric ionization of impurities, as well as to evaluate current density in QWire in the electric field longitudinal with respect to its axis.
Materials and methods. For the case of D(-)-center in InSb QWire the authors constructed curves of the dependence of the average binding energy of the impurity state, the average energy of the ground state of the electron and current density on the electric field strength. The short-range potential of D(-)- center was modelled by the zero-radius potential. The dispersion equation for D(-)- state of the electron in QWire at the presence of the longitudinal electric field was obtained in the effective mass approximation. The expression for the current density was obtained using an electroneutrality equation.
Results. The conductivity of a semiconductor QWire with a parabolic confinement potential was studied within the framework of the zero-range potential model, containing donor impurities, in the electric field longitudinal with respect to its axis at low temperatures. A dispersion equation determining the dependence of the binding energy of the impurity on the electric field strength was obtained. The authors calculated the width of the impurity level which was a nonlinear increasing function of electric field strength. It has been found that the impurity level width decreases with an increase of its depth. It has been shown that the bound state of an electron on an impurity is destroyed by a strong electric field, i.e. the thermoelectric phenomenon of ionization occurs. It has been discovered that under conditions of low temperatures the dependence of the current density in a QWire in the longitudinal electric field has a superlinear character. It has been revealed that the ionization electric field strength increases with an increase of the average binding energy of the impurity. The researches have found that the current density dependence on theИlongitudinal electric field strength have a superlinear character in conditions of low temperatures in QWire in the approximation of constant mobility of electrons.
Conclusions. From the fundamental point of view, the considered effect of thermoelectric ionization allows to calculate the average binding energy, to determine the concentration of impurity states in QWire and to estimate the temperature of impurity exhaustion. As for the point of view of application – it allows to control th
concentration of free charge carriers and, hence, electrical conductivity of QWire. In addition, an external electric field allows to influence the broadening of impurity quasistationary states, i.e. to change their life time.
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