A new erasing method for a single-voltage long-endurance flashmemory

A new method to erase a standard (double-poly, stacked-gate NOR-type) flash cell is proposed. The method, still using the tunneling mechanism to extract electrons from the floating gate, is based on the concept of keeping the electric field constant during the whole erasing operation. The new method has two main advantages with respect to the conventional one: (1) it does not depend on the supply voltage variation and (2) it allows a better reliability in terms of endurance-induced stress. Results have shown that flash device performances are greatly improved in terms of stability and endurance reliability up to one million cycles     

Impact of Ge-Sb-Te compound engineering on the set operation performance in phase-change memories

The phase-change memory (PCM) technology is considered as one of the most attractive non-volatile memory concepts for next generation data storage. It relies on the ability of a chalcogenide material belonging to the Ge-Sb-Te compound system to reversibly change its phase between two stable states, namely the poly-crystalline low-resistive state and the amorphous high-resistive state, allowing the storage of the logical bit. A careful study of the phase-change material properties in terms of the set operation performance, the program window and the electrical switching parameters as a function of composition is very attractive in order to enlarge the possible PCM application spectrum. Concerning the set performance, a crystallization kinetics based interpretation of the observed behavior measured on different Ge-Sb-Te compounds is provided, allowing a physics-based comprehension of the reset-to-set transition.     

Electron mobility in ULSI MOSFETs: effect of interface traps andoxide nitridation

We provide a comprehensive set of electron mobility measurements at 300 K and 77 K on standard and N₂O-nitrided MOSFETs, with channel doping in the range 3.8×10¹⁷-1.25×10¹⁸ cm^-3. In such heavily-doped devices, the Fermi level always lies very close to the conduction band edge, where interface traps reach the highest density and the shortest lifetimes. We show that these traps contribute to the gate-channel capacitance, leading to a systematic overestimate of the channel charge. This effect has the largest impact precisely in the roll-off region of the mobility curves, which has been the subject of recent theoretical investigations     

Resistive switching characteristics of NiO films deposited on top of W or Cu pillar bottom electrodes

This paper demonstrates the feasibility of resistive switching memory elements integrating a nickel oxide film deposited on top of a pillar bottom electrode. The unipolar switching was investigated over a wide temperature range (25 to 125 °C) on samples integrating either W or Cu plugs with diameters ranging from 1 down to 0.18 μm. The switching characteristics and scaling trends of various fabricated memory elements were compared to select the best bottom electrode contact. It was shown that NiO layers deposited on top of W-plugs exhibited the most satisfactory electrical characteristics for future high density memory devices. Their reliability performances in terms of endurance and retention were subsequently studied by using either quasi-static or pulse programming modes. Set operations with short (10 to 20 ns) and low amplitude (around 2 V) voltage pulses were also demonstrated.     

Non-local effects in p-MOSFET substrate hot-hole injectionexperiments

Extensive measurements of hot-hole injection probability from silicon into silicon dioxide covering a wide range of oxide fields and substrate biases are presented and compared with results previously published in the literature. It is found that, in the highly inhomogeneous electric fields typically needed to induce substrate hole injection, nonlocal effects take place that limit the possibility to accurately describe injection probability data by means of a unique set of lucky carrier model parameters     

Optical parameters of diode lasers based on an InAsSb/InAsSbP heterostructure

The rates of radiative recombination (including transitions induced by enhanced luminescence) and nonradiative recombination, internal quantum yield of luminescence, and the matrix element for band-to-band optical transitions were determined for the first time for InAsSb/InAsSbP diode lasers oscillating at wavelengths of 3.1–3.2 μm. It is established that the contribution of nonradiative recombination to the lasing threshold can be as large as 97%. The internal quantum yield of luminescence for the InAs_0.97Sb_0.03 compound is no higher than 3%. Most likely, the nonradiative channel is formed with involvement of Auger recombination with the constant C = 4.2 × 10^?38 m⁶s^?1 (T = 77 K). The studied samples of lasers feature relatively low optical losses ρ = 900 m^?1 and internal quantum efficiency of emission at the level of 0.6. The spontaneous lifetime of nonequilibrium charge carriers as determined from the radiative-recombination rate is equal to 6 × 10^?8 s, which is consistent with known published data.     

Homogeneous coordinates for computer graphics

Some mathematical aspects of homogeneous coordinates are presented. It is shown that the usual methods applied by workers in computer graphics are theoretically sound provided care is exercised in defining the range of the coordinate chart. The mechanics of the linear representation of transformations are explained in terms of commutative diagrams. Finally some familiar examples are discussed.     

Structural and energy characteristics of native vacancy-type defects in the biaxially stressed GaN lattice

For biaxially stressed GaN clusters, the structure, charges, and energies of the formation of intrinsic Ga and N vacancies are calculated by the quantum-chemical method in the SCF MO LCAO approximation taking into account relaxation of the crystalline surroundings. It is established that the use of substrates introducing compressive or tensile stresses into the epitaxial layer affects the concentrations of intrinsic vacancy-type point defects. This effect most clearly manifests itself in the nitrogen sublattice in the GaN crystal lattice, especially in the case of its tension, i.e., during the epitaxial grown of GaN on the Si substrate. Redistribution of the electron density in the defect region in the case of lattice compression or tension can be the cause of variation in the location of electronic levels of defects in the band gap of the crystal.     

Automated Lubricant Application in the Stamping of Gas-Turbine Blades

Russian Engineering Research - The main problems arising in the modernization of automated lubricant application in robotized stamping are outlined. A device for lubricant application to stamps is...     

Influence of Vibration on Surface Roughness in Turning

Russian Engineering Research - Errors in machining and the relation between the final surface roughness and the vibration of the machining system (the lathe, the attachment, the tool, and the...