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...     

Influence Exerted by Construction of Vertical Cylindrical Explosive Charges Increased in Diameter on the Degree of Ore Shattering

The results are presented for the laboratory and in-situ investigations into influence exerted by construction of the vertical cylindrical explosive charges on the degree of rock-mass shattering. The necessity is shown for creating the ascending workings with a cross-section up to 1m ². For the vertical concentrated charges with inert gaps, the drilling-and-blasting parameters ensuring a decrease in specific consumption of explosive for the secondary shattering are given.     

THz Stimulated Emission from Simple Superlattice in Positive Differential Conductivity Region

Narrow band emissions at 2.6–2.8 THz are observed out of liquid helium cooled 1 mm disk chips prepared of a wafer with the very low n type doped weak barrier GaAs–GaAlAs superlattice of 1000 periods. The emissions are at about 8.0–18.0 V pulsed voltage applied to the chips in region of the chips positive DC differential conductivity that guaranties absence of inhomogeneous electric field domains in the chips. The emission frequency bands are estimated with a cyclotron resonance filter; the measurements show that the band width is of about that of the THz quantum cascade laser. By using long voltage pulses the chip heating above 100 K is achieved without substantial change in emission power. We speculate that the emission is super luminescence (amplification) of whispering gallery modes in the chips as a result of inverted Wannier-Stark level transitions under bias. The results are the first world demonstration of THz stimulated emission in a simple superlattice within region of positive DC differential conductivity; they give strong impetus for development of THz and higher frequency sources based on such simple superlattices; the sources should well compete with the THz quantum cascade lasers in particular at elevated temperatures.     

Observation of a long-range action effect in ion-bombarded GaAs transistor structures

Changes in the carrier concentration and mobility in the active layers of Schottky-barrier field-effect transistors are observed when the structures are bombarded with argon ions on the nonworking side of the GaAs substrate. Pis’ma Zh. Tekh. Fiz. 25, 50–53 (August 26, 1999)     

Comparison of the Efficiency of Promising Heterostructure Frequency-Multiplier Diodes of the THz-Frequency Range

Semiconductors - The results of theoretical and experimental comparison of the signal-conversion efficiency by diodes based on superlattices with a small number of periods (N-like...     

InAlAs/InGaAs/InP High-Electron-Mobility Transistors with a Composite Channel and Higher Breakdown Characteristics

Technical Physics Letters - A high-electron-mobility transistor (HEMT) based on InAlAs/InGaAs/InP heterostructures possessing higher breakdown characteristics is developed. An InGaAs composite...     

Molecular-beam epitaxy of InGaAs/InAlAs/AlAs structures for heterobarrier varactors

The molecular-beam epitaxy of InGaAs/InAlAs/AlAs structures for heterobarrier varactors is studied and optimized. The choice of the substrate-holder temperature, growth rate and III/V ratio in the synthesis of individual heterostructure regions, the thickness of AlAs inserts and barrier-layer quality are critical parameters to achieve the optimal characteristics of heterobarrier varactors. The proposed triple-barrier structures of heterobarrier varactors with thin InGaAs strained layers immediately adjacent to an InAlAs/AlAs/InAlAs heterobarrier, mismatched with respect to the InP lattice constant at an AlAs insert thickness of 2.5 nm, provides a leakage current density at the level of the best values for heterobarrier varactor structures with 12 barriers and an insert thickness of 3 nm.