11 research outputs found
Experimental study of negative photoconductivity in n-PbTe(Ga) epitaxial films
We report on low-temperature photoconductivity (PC) in n-PbTe(Ga) epitaxial
films prepared by the hot-wall technique on -BaF_2 substrates. Variation
of the substrate temperature allowed us to change the resistivity of the films
from 10^8 down to 10_{-2} Ohm x cm at 4.2 K. The resistivity reduction is
associated with a slight excess of Ga concentration, disturbing the Fermi level
pinning within the energy gap of n-PbTe(Ga). PC has been measured under
continuous and pulse illumination in the temperature range 4.2-300 K. For films
of low resistivity, the photoresponse is composed of negative and positive
parts. Recombination processes for both effects are characterized by
nonexponential kinetics depending on the illumination pulse duration and
intensity. Analysis of the PC transient proves that the negative
photoconductivity cannot be explained in terms of nonequilibrium charge
carriers spatial separation of due to band modulation. Experimental results are
interpreted assuming the mixed valence of Ga in lead telluride and the
formation of centers with a negative correlation energy. Specifics of the PC
process is determined by the energy levels attributed to donor Ga III, acceptor
Ga I, and neutral Ga II states with respect to the crystal surrounding. The
energy level corresponding to the metastable state Ga II is supposed to occur
above the conduction band bottom, providing fast recombination rates for the
negative PC. The superposition of negative and positive PC is considered to be
dependent on the ratio of the densities of states corresponding to the donor
and acceptor impurity centers.Comment: 7 pages, 4 figure
Some theorems about spectrum and finite element approach for eigenvalue problems for elastic bodies with voids
MAKING MARKETING DECISIONS IN AN UNSTABLE ECONOMIC ENVIRONMENT
The chapter presents an analysis of current features and difficulties in developing and making marketing decisions in the framework of enterprise management in unstable economic conditions. To a large extent, these difficulties are related to the transition of Russian socioeconomic systems from a tradi-tional development model to a transformational one. Socioeconomic trans-formations are accompanied by crisis phenomena and processes in which enterprises are developing. Their effective functioning in the interests of economic growth requires the introduction and further development of marketing systems based on the principle of mutual improvement of the economic entity, the consumer and the external market agent, that is, the creation of anti-crisis marketing. The purpose of the study is to determine the specifics of making integrated marketing decisions and their nuances in the modern economic space. The main result of the study is to identify the impact of a difficult period in the functioning and development of the national economy on the transformation of marketing activities in enterprises. It is concluded that it is necessary to create a model for making anti-crisis marketing decisions, which will be characterized by its nonstandard nature, will be aimed at taking comprehensive, necessary measures and evaluating their effectiveness, taking into account both the short-and long-term prospects for the development of the system. © 2021 by Information Age Publishing