Igor P. Zvyagin

Professor of Physics (b. 1938)
Graduated from Moscow State University (1961)
Ph.D. in Physics (1964), Dr.Sci. (1981)
E-mail: scon281@phys.msu.ru
Phone: (495) 939-3731

Scientific interests:

Solid state theory, transport properties of semiconductors, hot electrons and domain electrical instability, transport in heavily doped crystalline and amorphous semiconductors, hopping conductivity, thermoelectric properties, disordered low-dimensional systems, theory of recombination in amorphous silicon.

Selected publications:

• I.P. Zvyagin. Electronic Superstructures in Doped Superlattices. Zh. Eksp. Teor. Fiz. [JETP] 114 (3), 1089-1100 (1998).

  We argue that in doped semiconductor superlattices with narrow quantum wells at low temperatures and at sufficiently low doping levels the ground state can correspond to inhomogeneous distribution of electrons over the wells. In fact, using the density functional approach, we show that under the above conditions the exchange-correlation contribution to the system energy can exceed the sum of the kinetic and Hartree energies, making the uniform distribution unstable. For GaAs/GaAlAs superlattices the estimate of the critical conditions for the loss of stability of the homogeneous state at T=0 K correspond to doping concentrations of about 10¹⁷cm^-3. Inhomogeneous ground states are discussed.

• A.G. Kazanskii, I.A. Kurova, N.N. Ormont, I.P. Zvyagin. Anomalous relaxation of light-induced states of a-Si:H. J. Non-Cryst. Sol. 227-230, 306 (1998).

• I.P. Zvyagin, M.A. Ormont. Vertical screening in doped semiconductor superlattices with intentional disorder. Fiz. Tech. Poluprov. [Semiconductors] 33(1), 79-82 (1999).

  We calculate the energy spectrum of doped semiconductor superlattices with intentional disorder taking account of the Coulomb interaction, originated from redistribution of electrons over the quantum wells. Using the density functional theory, we study numerically the effect of screening on vertical disorder, in particular, on the distribution of size quantization levels in these structures. We show that screening gives rise to a shift of the maximum of the level distribution and appreciable decrease of its width; this can produce delocalisation of electron states that determine vertical conductivity of the structure.

• I.P. Zvyagin. Vertical hopping conduction via virtual states in intentionally disordered superlattices. Pis'ma Zh. Eksp. Teor. Fiz. [JETP Letters] 69(12), 932-937 (1999).

  A new mechanism of vertical conduction in intentionally disordered superlattices is examined. It is shown that low-temperature conduction due to phonon-assisted tunneling between distant quantum wells of a superlattice is determined mainly by hopping processes via virtual intermediate states. Under standard conditions a weak temperature dependence of vertical conductivity is obtained for this mechanism. The characteristic behavior of the conductivity as a function of disorder amplitude is found for this mechanism.

• P. Thomas, I.P. Zvyagin. Radiation related to electrically driven oscillations in doped double quantum well structures. Phys. Status Solidi B 218(2), 449-453 (2000).

• I.P. Zvyagin, M.A. Ormont, K.E. Borisov. Hopping transport equation for electrons in superlattices with vertical disorder. Nanotechnology 11(4), 375 (2000).

• I.P. Zvyagin, R. Keiper. Conduction in Granular Metals by Hopping via Virtual States. Philosophical Magazine B 81(9), 997 (2001).

• I.P. Zvaygin, S.D. Baranovskii, P. Thomas, H. Cordes, K. Kohary. Hopping in Quasi-One-Dimensional Disordered Solids: Beyond the Nearest-Neighbor Approximation. Phys. Status Solidi B 230(1), 227 (2002).

• I.P. Zvyagin, M.A. Ormont, S.D. Baranovskii, P. Thomas. Effect of Coulomb Interactions on the Density of States in Intentionally Disordered Superlattices. Phys. Status Solidi B 230(1), 193 (2002).

• I.P. Zvyagin, R. Keiper. Conduction in Granular Metals by Virtual Tunneling on the Fractal Percolation Cluster. Phys. Status Solidi B 230(1), 151 (2002).

• S.D. Baranovskii, I.P. Zvyagin, H. Cordes, S. Yamasaki, P. Thomas. Percolation Approach to Hopping Transport in Organic Disordered Solids. Phys. Status Solidi B 230(1), 281 (2002).

• S.D. Baranovskii, I.P. Zvyagin, H. Cordes, S. Yamasaki, P. Thomas. Electronic transport in disordered organic and inorganic semiconductors. J. Non-Cryst. Solids 299-302, Part 1, 416-419 (2002).

• I.P. Zvyagin, I.A. Kurova, N.N. Ormont. Variable range hopping in hydrogenated amorphous silicon. Phys. Status Solidi C 1, 101-104 (2004).

• I.P. Zvyagin. Generalized pair approximation in the description of the AC conductivity of a dense disordered array of quantum dots. Phys. Status Solidi C 3, 300-303 (2006).