scholarly journals Прыжковая проводимость Мотта и Эфроса-Шкловского в пленках из наночастц Si, легированных фосфором и бором

2022 ◽  
Vol 56 (2) ◽  
pp. 204
Author(s):  
С.Г. Дорофеев ◽  
Н.Н. Кононов ◽  
С.С. Бубенов ◽  
В.М. Попеленский ◽  
А.А. Винокуров
Keyword(s):  
Transport Parameters ◽  
Free Electrons ◽  
Thermally Activated ◽  
Si Nanoparticles ◽  
Medium Level ◽  
Temperature Dependences ◽  
Type Variable ◽  
Heavily Doped ◽  
Si Films ◽  
Variable Range Hopping Conduction

The electrical characteristics of thin films formed from Si nanoparticles (nc-Si) with various degrees of doping are studied. To exclude the influence of ionic conductivity, the current parameters of the films were recorded in an ultrahigh vacuum (P ~ 3 – 5∙10–9 Torr) with preliminary high-temperature (9500C) annealing. An analysis of the temperature dependences of the conductivity showed that in nc-Si films formed from heavily doped nanoparticles (the concentration of free electrons ne is greater than 1019 cm-3), the transport is determined by variable-length hopping (VRH). In these samples, the Mott conductivity prevails at temperatures above 300C and at lower temperatures, the Efros-Shklovskii type variable range hopping conduction is dominate. In films with a medium level of doping of nanoparticles (ne <1019 cm-3), transport is realized by the Mott, Efros - Shklovskii and thermally activated conductivities. At the same time, thermally activated conductivity is dominated at temperatures above 560K. In nc-Si films formed from undoped nanoparticles, the transport parameters are determined by thermally activated conductivity and Mott's conductivity. Conductivity of Efros - Shklovskii is not observed in such films. From the analysis of the parameters corresponding to the Mott and Efros - Shklovsky conductivities, the localization lengths of wave functions, the density of states at the Fermi level (g (EF)), and average hopping lengths are found. The average hopping lengths in nc-Si films from nanoparticles pre-etched in HF are in the range 56 - 86 nm, which indicates that hopping in such films occurs via intermediate nanoparticles.

The optical and electronic properties of semiconducting diamond

1993 ◽  
Vol 342 (1664) ◽  
pp. 233-244 ◽  
Keyword(s):  
Absorption Spectrum ◽  
Electronic Properties ◽  
Valence Band ◽  
Chemical Vapour ◽  
Impurity Band ◽  
Thermally Activated ◽  
Boron Doped ◽  
Optical And Electronic Properties ◽  
Temperature Dependences ◽  
Semiconducting Diamond

In this paper I review the evidence that shows that the optical and electronic properties of semiconducting diamond can be understood in terms of boron acceptors partially compensated by deep donors. In natural semiconducting diamond, in which the total impurity concentration is less than 1 ppm, there is a lot of fine structure in the acceptor absorption spectrum that is not fully understood, and the electrical conductivity is primarily associated with the thermally activated excitation of holes from the acceptor ground state to the valence band. Some of the problems regarding the analysis of Hall effect data in this material are discussed, including the temperature dependences of the scattering mechanisms, of the contribution from the split-off valence band and of the population of excited states. There are no adequate theoretical descriptions of any of these processes, and this leads to some uncertainties in the values of the parameters derived from the temperature dependence of the Hall coefficient. For boron-doped synthetic diamond, and thin film diamond grown by chemical vapour deposition (CVD), the defect concentrations are generally much higher, and much more inhomogeneous, than in natural semiconducting diamond. This results in a substantial broadening of the acceptor absorption spectrum and the electronic properties are greatly modified by increasing contributions from impurity band conduction as the acceptor concentrations are increased, leading to very low mobility values. For both poly crystalline and single crystal homoepitaxial CVD diamond, measurements of the electrical properties can be completely invalidated by the presence of a surface layer of non-diamond carbon.

Charge ordering and ferroelectric states in organic quasi-one-dimensional conductors

2002 ◽  
Vol 12 (9) ◽  
pp. 133-138
Author(s):  
F. Nad ◽  
P. Monceau
Keyword(s):  
Phase Transitions ◽  
Charge Ordering ◽  
Electron Interaction ◽  
Charge Symmetry ◽  
Low Frequencies ◽  
One Dimensional ◽  
Thermally Activated ◽  
Correlated Electron ◽  
Temperature Dependences ◽  
New Phase

In quasi-one-dimensional (TMTTF)2X conductors [1], where X are the various centro-symmetrical and non-centrosymmetrical anions, by study of temperature dependences of conductance G and dielectric permittivity $\varepsilon '$ at low frequencies we have found anomalies which are characteristic for phase transitions: an abrupt bend on the G(l/T) dependences with thermally activated decrease of G and sharp maxima of the E' near the charge ordering temperature corresponding to the E' divergence according to the Curie law. A number of evidences have been obtained in favor that driving force of these phase transitions is the long range correlated electron interaction yielding the charge ordering along the molecular chains (a lattice version of the Wigner crystal). The anion chains, electrically balanced with molecular chains, are of very importance in the formation and the stabilization of these new phase states. It appears that the form of charge symmetry of the anions determines to a great extent the types of the occurring transitions and the developing ground states.

Metastable Defect Kinetics in Hydrogen Passivated Polycrystalline Silicon

1994 ◽  
Vol 336 ◽  
Author(s):  
N. H. Nickel ◽  
R. A. Street ◽  
W. B. Jackson ◽  
N. M. Johnson
Keyword(s):  
Temperature Dependence ◽  
Polycrystalline Silicon ◽  
Direct Evidence ◽  
Slow Cool ◽  
Dark Conductivity ◽  
Active Hydrogen ◽  
Thermally Activated ◽  
Rate Dependent ◽  
Si Films ◽  
Metastable Defect

ABSTRACTThe temperature dependence of the dark conductivity, σD, of unhydrogenated and hydrogen passivated polycrystalline silicon (poly-Si) films was Measured. While σD of unhydrogenated poly-Si did not exhibit any influence of thermal treatment prior to the measurement, striking effects were observed in hydrogenated poly-Si films. Below 268 K a cooling-rate dependent metastable change of σD is observed. The dark conductivity increases by more than 8 orders of magnitude. This frozen-in state is metastable: Annealing and a slow cool restore the temperature dependence of the relaxed state. The time and temperature dependence of the relaxation reveal that this process is thermally activated with 0.74 eV. The lack of the quenching metastability in unhydrogenated poly-Si is direct evidence that the metastable changes in σD are due to the formation and dissociation of an electrically active hydrogen complex, in the grain-boundary regions.

scholarly journals Heat Effects Occurring in the Supercooled Liquid State and Upon Crystallization of Metallic Glasses as a Result of Thermally Activated Evolution of Their Defect Systems

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 417 ◽  
Author(s):  
Andrei Makarov ◽  
Gennadii Afonin ◽  
Yurii Mitrofanov ◽  
Nikolai Kobelev ◽  
Vitaly Khonik
Keyword(s):  
Metallic Glasses ◽  
Liquid State ◽  
Supercooled Liquid ◽  
Shear Moduli ◽  
Thermally Activated ◽  
Supercooled Liquid State ◽  
Heat Effects ◽  
Temperature Dependences ◽  
Defect System ◽  
Kinetics Of

We show that the kinetics of endothermal and exothermal effects occurring in the supercooled liquid state and upon crystallization of metallic glasses can be well reproduced using temperature dependences of their shear moduli. It is argued that the interrelation between the heat effects and shear modulus relaxation reflects thermally activated evolution of interstitial-type defect system inherited from the maternal melt.

Raman Scattering in Ultra Heavily Doped Si and Ge: The Dependence on Free Carrier and Substitutional Dopant Densities

1983 ◽  
Vol 23 ◽  
Author(s):  
A. Compaan ◽  
G. Contreras ◽  
M. Cardona ◽  
A. Axmann
Keyword(s):  
Pulsed Laser ◽  
Electronic Excitations ◽  
Phonon Coupling ◽  
Free Electrons ◽  
Phonon Softening ◽  
Local Modes ◽  
Optic Phonon ◽  
Low Mass ◽  
Heavily Doped ◽  
P Type

ABSTRACTWe present the results of a systematic study of phonon softening due to free electrons and holes in extremely heavily doped Si and Ge. Metastable concentrations of Bi, Sb, As, P, Al and B were implanted and pulsed laser annealed (ruby or XeCl) to produce substitutional concentrations up to 4×1021 cm−3 . We find softening of the zone center optic phonon of as much as ˜5% in p-type Ge, ˜5.4% in p-type Si, and 2% in n-type Si. The shifts are explained by phonon coupling to single particle electronic excitations. In addition we discuss the density dependence of the Raman-active vibrational local modes of P and Al in Ge and of B in Si which we demonstrate can provide a convenient measure of substitutional concentrations of these low mass dopants.

Studies of MOS and Heterojunction Devices Using Doped μc-Si and a-Si

1991 ◽  
Vol 219 ◽  
Author(s):  
D. R. Lee ◽  
C. H. Bjorkman ◽  
C. Wang ◽  
G. Lucovsky
Keyword(s):  
Photovoltaic Effect ◽  
Chemical Vapor ◽  
Flat Band ◽  
Mos Capacitor ◽  
Gate Electrodes ◽  
Mos Devices ◽  
Current Voltage ◽  
Heavily Doped ◽  
Si Films ◽  
Band Structure Model

ABSTRACTCurrent-voltage voltage characteristics of heterojunctions formed by remote plasma enhanced chemical vapor deposition (PECVD) of heavily doped μc-Si onto doped c-Si have been studied, as well as capacitance-voltage characteristics of MOS capacitor structures using heavily doped remote PECVD μc-Si and a-Si films as gate electrodes on thermally oxidized crystalline Si. Shifts in the flat-band voltages of MOS devices using the μc-Si and a-Si as gate electrodes relative to that of a reference Al/SiO2/c-Si structure are measured and explained in terms of a band structure model for the μc-Si and a-Si. Rectification and a photovoltaic effect observed in the pn heterojunctions are also explained in context of the same model.

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