Multilevel Recording in Ge2Sb2Te5 Thin Films

Semiconductors - The current–voltage characteristics measured on Ge2Sb2Te5 thin films in the current mode are studied. The effect of multilevel recording is established when applying...     

Ultra-Robust Flexible Electronics by Laser-Driven Polymer-Nanomaterials Integration

Polyethylene terephthalate (PET) is the most widely used polymer in the world. For the first time, the laser-driven integration of aluminum nanoparticles (Al NPs) into PET to realize a laser-induced graphene/Al NPs/polymer composite, which demonstrates excellent toughness and high electrical conductivity with the formation of aluminum carbide into the polymer is shown. The conductive structures show an impressive mechanical resistance against >10000 bending cycles, projectile impact, hammering, abrasion, and structural and chemical stability when in contact with different solvents (ethanol, water, and aqueous electrolytes). Devices including thermal heaters, carbon electrodes for energy storage, electrochemical and bending sensors show this technology's practical application for ultra-robust polymer electronics. This laser-based technology can be extended to integrating other nanomaterials and create hybrid graphene-based structures with excellent properties in a wide range of flexible electronics’ applications.     

Efficient electro-optic semiconductor medium based on type-II heterostructures

An electro-optic medium based on the type-II semiconductor superlattice is proposed. Electrooptic modulation of the intensity of optical reflectance of the electro-optic medium integrated into a vertical Fabry-Perot cavity is studied by the optical-reflectance-spectroscopy method. The experimental data are approximated using an oscillator model of exciton absorption. The efficiency of the electro-optic medium in the case of detuning from the absorption peak by 50 meV in electric fields of 0–50 kV/cm is 10^?9 m/V at a medium filling factor of 100%.     

Potentiometric determination of the content of water-soluble organic amides

A method was developed for determining water-soluble, nitrogen-containing organic compounds based on their potentiometric titration with a polarized platinum microelectrode in HCl medium with a solution of tungstophosphoric heteropolyacid. The range of determinable concentrations is 0.4–65%. The method is characterized by good reproducibility (S_r no greater than 0.02–0.04) both for model and for process solutions. The duration of the analysis to determine the DMAA content using tungstophosphoric heteropolyacid is a maximum of 15 min. __________ Translated from Khimicheskie Volokna, No. 1, pp. 55–57, January–February, 2007.     

Effect of coulomb correlations on luminescence and absorption in compensated semiconductors

The spectra of donor–acceptor light absorption and luminescence in lightly doped and lightly compensated semiconductors are calculated. In the photoluminescence calculation, two limiting cases of long and short carrier lifetimes relative to the carrier-energy relaxation time are considered. It is shown that, at long lifetimes, the photoluminescence spectrum is significantly shifted toward longer wavelengths due to the relaxation of minority charge carriers. At intermediate lifetimes, the photoluminescence spectrum consists of two peaks, which is in good agreement with the experimental data.     

Electrical properties and transport mechanisms in phase change memory thin films of quasi-binary-line GeTe–Sb<Subscript>2</Subscript>Te<Subscript>3</Subscript> chalcogenide semiconductors

The temperature dependences of the resistivity and current–voltage (I–V) characteristics of phase change memory thin films based on quasi-binary-line GeTe–Sb₂Te₃ chalcogenide semiconductors Ge₂Sb₂Te₅, GeSb₂Te₅, and GeSb₄Te₇ are investigated. The effect of composition variation along the quasibinary line on the electrical properties and transport mechanisms of the thin films is studied. The existence of three ranges with different I–V characteristics is established. The position and concentration of energy levels controlling carrier transport are estimated. The results obtained show that the electrical properties of the thin films can significantly change during a shift along the quasi-binary line GeTe–Sb₂Te₃, which is important for targeted optimization of the phase change memory technology.     

Physics of switching and memory effects in chalcogenide glassy semiconductors

Switching and memory effects in chalcogenide glassy semiconductors have been known for nearly fifty years. However, the physics of these effects remains unclear. Recent interest in this problem is caused by active developments of a new generation nonvolatile memory based on the chalcogenide glass-crystal phase transition. In this paper, we review the main experimental features of switching and memory effects, review and analyze the models of the switching effect. Consider the main characteristics of phase-change memory cells made of various materials. On these grounds, the main advantages of modern phase-change memory cells are presented in comparison with first-generation memory elements.