There are presented research data of ESR, photoluminescence (PL) and carrent transport in porous silicon (PS) on KDB-0.3 and KES-0.01 Si, oxidized by10 minute isochronous thermal annealing on air at temperatures Tann from 20°С to 900°С and also in HNO3 for the purpose of the further clearing of Pb - centres nature of no radiating recombination. Maximum quantum yield of PL was observed at chemical oxidation of the PS on silicon of KDB-0.3 mark.. Anticorrelation of PL and ESR intensities of Pb - centres in the range of Tann = (20-300) °С takes a place. . Nonmonotonic dependence of ESR intensity of Pb - centres vs Tann with a minimum nearby 700°С is found out. Weak PL in PS with Tann nearby 700°С at minimum of ESR of Pb - centres means occurrence with annealing of other no radiating recombination centres. Falling of conductivity of PS with growth of Tann is connected with disintegration of Si fibres in Ps on small granules through which there is a discrete tunneling of current carriers.

Porous silicon is formed using pulsed current with a pulse modulation varied in a range spanning five orders of magnitude, starting from a hundredth of a second, in order to achieve modulation of the properties of PS on the nanoscale. The PS is characterized by performing photoluminescence (PL), paramagnetic, and charge transport measurements. We find that the properties of prepared PS are greatly affected by the modulation period applied and depend on it in a nonmonotonic way. The intensity of orange-red PL exhibits a resonance-like behavior reaching a maximum at the modulation period in the range of 0.1–0.25 s. A correlation between the variation in PL intensity and the electron paramagnetic resonance signal is noticed. We show that PS with a porosity of 50% and a distance between pores of 10 nm is mainly consists of air and silicon oxide. In the prepared PS, the silicon, in the form of granules with a diameter of ≈1.5 nm arranged in chainlets, has a volume fraction on the order of 1%.

AbstractPorous silicon is formed using pulsed current with a pulse modulation varied in a range spanning five orders of magnitude, starting from a hundredth of a second, in order to achieve modulation of the properties of PS on the nanoscale. The PS is characterized by performing photoluminescence (PL), paramagnetic, and charge transport measurements. We find that the properties of prepared PS are greatly affected by the modulation period applied and depend on it in a nonmonotonic way. The intensity of orange-red PL exhibits a resonance-like behavior reaching a maximum at the modulation period in the range of 0.1–0.25 s. A correlation between the variation in PL intensity and the electron paramagnetic resonance signal is noticed. We show that PS with a porosity of 50% and a distance between pores of 10 nm is mainly consists of air and silicon oxide. In the prepared PS, the silicon, in the form of granules with a diameter of ≈1.5 nm arranged in chainlets, has a volume fraction on the order of 1%.

We present the data on changes in the properties of porous silicon formed at the current pulse modulation in the range of 0.1–1 Hz with the aim to modulate the properties of porous silicon in a nanoscale range. It is demonstrated that the use of the pulsed mode of formation of porous silicon with a period of a few tenths of a second can dramatically affect the photoluminescence quantum yield and other properties of the material. There is a correlation of the luminescent, electrotransport, and paramagnetic properties of porous silicon formed under different modes.

Представлены данные изменения свойств пористого кремния (ПК), сформированного при импульсной модуляции тока в диапазоне (0.1-1) Hz с целью нанометровой модуляции свойств ПК. Показано, что применение импульсного режима формирования ПК с периодом в десятые доли секунды может существенно повлиять на квантовый выход фотолюминесценции и другие свойства ПК. Имеется корреляция люминесцентных, электротранспортных и парамагнитных свойств ПК, сформированного в различных режимах. DOI: 10.21883/FTT.2017.02.44042.275

Using transmission electron microscopy and elemental analysis, it has been shown that tungsten telluride glass (TTG) containing erbium and ytterbium as impurities penetrates into pores of porous silicon (PS) when melted in vacuum at 500°C. It has been found that the intensity of photoluminescence (PL) of erbium at the wavelength of 1.54 μm in PS: TTG layers increases by a factor of up to 5 in the layers irradiated by P + and Ar + ions. This is assigned to ion mixing which favors interaction among the Er ions and PS-embedded Si nanocrystals initiating sensitization of the PL, as well as to broadening of the glass-impregnated PS region. Implantation of the lighter Ne + ions affects only weakly the PL of erbium ions.

Work is devoted to physics of current transport in a wide class of the hetero-phase granulated mediums and similar systems with set of metal or semi-conductor granules, quantum dots or potential wells in which the exit from Coulomb blockade tunneling regime can be not observable because of irreversible breakdown and destruction of structure of medium. Such systems also concern and the condensed mediums with short distanced atoms of transition elements. In article for small and average electric fields the analytical decision of a stationary problem of discrete electronic transport through a chain of as much as big number of metal granules in area Coulomb tunneling blockade is performed. It is deduced the exponential law of growth of a current with electric field in such granulated systems. The characteristic feature of discrete tunneling in such medium is the volt-ampere characteristic type I exp(V/(N+1)kT) with great value N>> 1. Examples of application of the theory for explanation of current transport in porous silicon, synthesised by ionic implantation of nitrogen in silicon layers of nitride of silicon or glass like amorphous semiconductors are resulted.

It has been shown that the presence of silicon nanoparticles in a layer of porous silicon saturated with tungsten-tellurite glass causes an increase in the photoluminescence quantum efficiency of erbium (1530 nm) by an order of magnitude in the case of long-wavelength excitation and an enhancement of the ytterbium photoluminescence (980 nm) by almost 50 times and erbium photoluminescence by 25 times in the case of short-wavelength pumping. This luminescence enhancement is explained by the formation of additional channels of transfer of external excitation by silicon nanocrystallites in porous silicon to impurity ytterbium and erbium ions in tungsten-tellurite glass.

Experimental data obtained in the study of transverse current transport in a number of nanosized grained or similar media, such as porous silicon layers, anodic silicon oxide layers, and silicon nitride layers prepared by ion implantation of nitrogen into silicon, have been analyzed within the theory of discrete tunneling. It has been demonstrated that the measurements of current-voltage characteristics of diode structures with dielectric interlayers and embedded grains make it possible to obtain useful information on the character and sizes of grains or quantum dots in the nanosized grained medium. Amorphous dielectrics can be considered a grained medium with nanosized composition fluctuations. The current-voltage characteristics of real structures are determined by both the current nonlinearity associated with the charge carrier injection and the field nonlinearity caused by the Coulomb blockade of tunneling.

In this paper, we solve the problem of discrete electronic transport through a chain of an arbitrarily large number of metal granules in the region of Coulomb blockade of tunneling. The exponential law of current growth with increasing electrical field in the granular medium is deduced. We present the examples of applying the theory to explain the current transport in the glasslike amorphous semiconductors, the porous silicon, and the silicon-nitride layers synthesized in silicon by the ion implantation of nitrogen. The similar exponential growth of the current is also possible in condensed media with closely spaced atoms of transition elements. such behavior can actually be observed in the nanosized thin-film samples at low temperatures.

Forsterite doped with Cr 4+ ions is prepared in silicon-based structures according to a simple technique. These structures are of interest due to the characteristic luminescence in the near-IR range. Forsterite is synthesized by impregnation of porous silicon layers on n + -Si and p + -Si substrates with subsequent annealing in air. A photoluminescence response at a wavelength of 1.15 μm is observed at room temperature in porous silicon layers doped with magnesium and chromium for which the optimum annealing temperature is close to 700°C. The photoluminescence spectrum of porous silicon on the p + -Si substrate contains a broad band at a wavelength of approximately 1.2 μm. This band does not depend on the annealing temperature and the magnesium and chromium content and is most likely associated with the presence of dislocations in silicon. The experimental EPR data and eletrical properties of the structures are discussed. It is found that layers of pure porous silicon and chromium-doped porous silicon on n + -Si subtructures exhibit indications of discrete electron tunneling.

Results of an experimental observation of the voltage oscillations associated with a discrete tunneling of holes in porous silicon at room temperature are presented. The noise characteristics of diode structures with a porous silicon interlayer formed on heavily boron-doped silicon single crystals are studied. Peaks of excessive noise are observed at frequencies of ∼1 MHz, at which single-electron oscillations should be expected. The peak noise power is found to increase with current according to the ∼2.5 power law and, at a current density of 0.15 A/cm2, to exceed the noise power of the receiver by three to four orders of magnitude. The complex shape of the noise spectrum and its extension to the higher frequency region with increasing current are explained by the three-dimensionality of the system of nanometer-sized silicon grains embedded in insulating silicon dioxide of porous silicon.