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SEMICONDUCTOR PHYSICS

OPTICAL AND PHOTOELECTRICAL PROPERTIES OF SEMICONDUCTOR

CRYSTALS AND FILMS


Porous silicon consist of nanowires and nanoparticles, and due to quantum confinement exhibits visible photo- and electroluminescence at room temperature observable with naked eye. The increasing usage of por-Si in technological applications such as in light-emitting diodes, photonic crystals, gas testing devices, biological testing equipments, antireflection coating of solar cells has led to a particular wide area of research regarding its physical and chemical properties.

A2B6 and A3B6 type solid solution films are the basic materials for solar cells and negatron elements. They are suitable for creation of photoresistors, photoluminescent materials, p-n junctions, inject diodes, MIS-structures and can be useful in micro- and nanoelectronics.

Sheelite-type crystals are used for various optoelectronic devices, in particular, for fast-response acousto-optic deflectors and scanners. Sillenites are used as photosensitive reversible medium for recording and processing of optical date on a real scale of time.


TOPICS OF INVESTIGATION

  • Photo- and electroluminescence of porous silicon obtained by electrochemical and chemical etching
  • electronic properties of А2В6 type solid solution films, heterojunctions of А2В6 type solid solution films for solar cell, negatron phenomenon in А2В6 type solid solution thin films.
  • Investigation of emission and electrophysical parameters of metal – semiconductor contacts with amorphous and monocrystalline metal layer
  • Investigation of influence of plasma on morphology of semiconductor’s surface nanostructure

MAIN RESULTS

F.A. Rustamov, N.H. Darvishov, M.Z. Mamedov, E.Y. Bobrova, H.O. Qafarova

Influence of acetic acid on dynamics of etching process and morphology of stain porous silicon obtained at oxidant insufficiency is investigated. The optimum composition of a solution HF/HNO3/CH3COOH is defined. Obtained lateral homogeneous films of nanoporous silicon of a various thickness possess a visible photoluminescence.

F.A. Rustamov, M.Z. Mamedov,N.H. Darvishov

The technology of obtaining of luminescent nanoporous silicon in high-ohmic monocrystalline wafers of p-type with (111) and (100) orientation is developed. Change of luminescence and exitation spectra of the obtained films is investigated at ambient laboratory conditions. It is shown that maximum of both the photoluminescence and exitation spectra are shifted to short-wave region and thus the width of the optical  bandgap broaden from 1.95 eV to 2.3 eV.

 

Rustamov F.A.

For the stationary case a two-level model of simultaneous read-write of holographic grating in photorefractive crystals was developed. Based on the two-level model of recording and read-out of dynamic holographic gratings, precise expressions for wave amplitudes, diffraction efficiency and the gain coefficient were obtained. The problem of positive and negative feedback effects during simultaneous reading and writing of dynamic holograms in photorefractive crystals was solved analytically. It was demonstrated, that the diffraction efficiency and the gain coefficient are nonlinear functions of the readout beam intensity and nonreciprocal with respect to the readout from the two input ports. The possibility of achieving, under positive feedback, a maximum value of diffraction efficiency and complete energy transfer in a finite thickness of photorefractive crystal was shown.

Muradov S.R., Rustamov F.A., Sharbatov V.K.

For the non-stationary case a two-level model of simultaneous read-write of holographic grating in photorefractive crystals was developed. The recurrent relationships both for the internal field amplitudes and for the amplitudes of the optic waves involved in interactions were obtained. The obtained results were used for analysis of the simultaneous read-write dynamics in Bi12SiO20 crystals. Simple solution for the coupled partial differential equations, that leads to analytic formula for the diffraction efficiency, was obtained.

Rustamov F.A., Mamedov M.Z., Darvishov N.H.

The technology of macro porous silicon preparation in high resistant p-type silicon with (111) orientation has been developed. Emission and excitation spectra of obtained porous Si films have been studied. It is shown that photoluminescence spectrum of these films reaches its maximum at ~1.9 eV and is almost stable in time.

Abdinov A.Sh., Jafarov M.A., Nasirov E.F.

The deposition technology of А2В6 type thin films on the ceramic, glass, quartz and aluminum substrates was developed, and their photoelectric and electronic properties were investigated. Depending on a technological mode of the deposition and heat treatment regimes, the photo-chemical reaction, photoelectric memory and negative infrared photoconductivity in Cd1-хZnхS, Cd1-хZnхSе and CdS1-хSeх films were observed. Wide-band Cd1-хZnхS, Cd1-хZnхSе and CdS1-хSeхfilms possess the high photosensitivity and are perspective materials for creation of sources and receivers of the radiation in the visible and infrared spectral regions.

Jafarov M.A.

The influence of the intermediate Al2O3 layer on the switching effect and the steady conditions of conductivity in the sandwiched Al-CdS films was observed. It was established, that the presence of the р-type СdS nano-size inverse layer with high concentration of holes, controlled by technological conditions of the film deposition, in addition to existing Аl-n-СdS barrier, causes the formation of the reverse-biased p-n transition.

Jafarov M.A., Nasirov E.F.

By chemical deposition from water solution Cu2S-Cd1-xZnxS, Cu2Se-Cd1-xZnxSe, Cd1-xZnxS-CdS1-xSex, Cd0.4Zn0.6S/CdSе0.5Тe0,5 heterojunctions were manufacturedand their electric and photoelectric properties were investigated. Because of the high optic absorption coefficient and versatile optic and electric properties, which can be controlled by variation of a composition, heat-treatment regimes, the ternary compounds, like Cd1-xZnxS, Cd1-xZnxSe and CdS1-хSeх are considered as promising materials for solar cells.

Jafarov M.A., Nasirov E.F.

The negatron phenomena in Cd1-хZnхS, Cd1-хZnхSе and CdS1-хSeх thin films were investigated. The nonlinear current-voltage characteristics, such as negative differential resistance, negative photoconductivity, negative differential photoconductivity and the negative photo capacitor effect found out in the filmsCd1-хZnхS, Cd1-хZnхSе and CdS1-хSeх , were studied. These effects were explained using the uniform electronic-molecular mechanism. It was demonstrated, that negative photoconductivity is a function of the sizes of inter-crystallite barriers and nano-crystallites, and was caused by formation of nano-size electric domains inside the films.

Jafarov M.A.

The electric properties of the In2Te3 and FeTe single crystals were investigated. The current-voltage characteristics of the (InTe)1-x (PbTe)x single crystals under high external electric fields were analyzed. The switching effect in the In2Te3(Fe), In2Te3(Co) and In2Te3(Cr) single crystals were observed. It was established, that depending on the nature and concentration of the metals (Fe, Co, Cr) in the In2Te3 single crystals, the switching mechanisms (pure electron, the electron-heat, the heat-electron and pure heat) change.

Bagiev V.E., Darvishov N.G.

The investigation of the radiation and absorption spectra of the sillenite and sheelite-type compounds were carried out. An analysis of optic functions, that can give useful information on properties of the electron energy spectra of these crystals, was done. The characteristic features of the band structure of sillenite and seelite-type crystals were obtained by using the vacuum UV synchrotron radiation.

Bagiev V.E., Darvishov N.G.

The thermo- and photo-stimulated processes in Bi12SiO20, Bi12GeO20, Bi12TiO20 were investigated and parameters of the impurity center were determined. Conditions for appearance of photoelectric fatigue phenomenon, its stores and disappearance were investigated. The interconnection of the photoelectret state and CVC nonlinearity of structure M–Bi12MeO20–M was revealed. It was shown that exhaustion of trapping levels of crystals leads to effective screening of the external field.

Lebedeva N.N., Orbukh V.I.

Optic properties of the strontium titanat, litium niobat, barium-strontium niobat, lead magnesium niobat, antimony sulfoiodide compounds in the region from IR to UV; electric and photoelectric properties and residual photoelectric phenomena in highly disordered materials were investigated. Influence of photo carries on the structure of the domains and their polarization in ferroelectrics were studied.

Lebedeva N.N., Orbukh V.I.

Photoionization converter of the IR-radiation to the visible radiation was constructed on the basis of the semi-isolating semiconductor electrode GaAs doped with Cr. This converter was used as a device for nondestructive express-control for revealing inhomogeneity of the resistivity and disordering of crystalline microstructure in crystals, for obtaining a non-silver photographic image, plasma etching of the surface of a semiconductor.

 

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