Effect of rapid thermal annealing on properties of contacts Au-Mo-TiBx-GaAs

The analytical, structural and electrophysical techniques have been applied to studies of the thermal degradation mechanism appearing in diode structures with the Schottky barrier Au-Mo-TiBxGaAs. It was shown that the rapid thermal annealing at T = 600 °C during 60 sec in hydrogen atmosphere results in creating the ELS type center in the space charge region of GaAs. This center is represented by the complex VGa+VAs, which has been confirmed by photoluminescence measurements. It causes the appearance of excess current at the initial part of current-voltage characteristic

Radiation hardness of AlAs/GaAs-based resonant tunneling diodes

The total dose effects of ⁶⁰Co γ-radiation on the electrical properties of double-barrier Resonant Tunneling Diodes have been studied. The devices manifest enhanced radiation hardness and conserve their operating parameters up to doses of 2×10⁹ rad. It is shown that all changes in the current-voltage characteristics stem from the effect of ionizing radiation on the undoped layers. The radiation-stimulated diffusion of the heteropair components in the contact region is shown to be important for the voltage drop distribution

Memory Behavior of the Planar Hall Effect in Ferromagnetic (Ga, Mn)As/GaAs Superlattices

The planar Hall effect (PHE) has been studied in short period (Ga, Mn)As/GaAs superlattices displaying a ferromagnetic interlayer coupling between the magnetic layers. Complex dependence of the PHE on applied magnetic field is explained by taking into account the magnetocrystalline anisotropy of the (Ga, Mn)As layers, which results from biaxial compressive strain in the layers epitaxially grown on GaAs. Two-state behavior of the planar Hall resistance at zero magnetic field provides its usefulness for applications in nonvolatile memory devices. In addition, using an appropriate sequence of applied magnetic fields four different states of the planar Hall resistance, suitable for quaternary memory devices, can be realized owing to the formation of a stable multidomain structure in the Hall bar

Remnant magnetoresistance in ferromagnetic (Ga,Mn)As nanostructures

The authors show a magnetoresistive effect that appears in a lithographically shaped, three-arm nanostructure fabricated from ferromagnetic (Ga,Mn)As layers. The effect, related to a rearrangement of magnetic domain walls between different pairs of arms in the structure, is revealed as a dependence of zero-field resistance on the direction of the previously applied magnetic field. This effect could allow designing devices with unique switching and memory properties

Magnetoresistive memory in ferromagnetic (Ga,Mn)As nanostructures

Magneto-resistive nanostructures have been investigated. The structures were fabricated by electron beam lithography patterning and chemical etching from thin epitaxial layers of the ferromagnetic semiconductor (Ga,Mn)As, in shape of three nanowires joined in one point and forming three-terminal devices, in which an electric current can be driven through any of the three pairs of nanowires. In these devices, a novel magneto-resistive memory effect has been demonstrated, related to a rearrangement of magnetic domain walls between different pairs of nanowires in the device consisting in that its zero-field resistance depends on the direction of previously applied magnetic field. The nanostructures can thus work as two-state devices providing basic elements of nonvolatile memory cells

Bistability of (Ga,Mn)As Ferromagnetic Nanostructures Due to the Domain Walls Switching

We designed and investigated four-arm nanostructures, composed of two perpendicularly crossed stripes, fabricated from ferromagnetic (Ga,Mn)As layer by means of electron-beam lithography patterning and chemical etching. The nanostructures exhibit a bistable resistance behavior resulting from two configurations of magnetic domain walls in the central part of the structures. We demonstrate a possibility of switching between two stable resistance states in zero magnetic field by applying a pulse of either weak magnetic field or electric current through the structure

Planar Hall Effect in Ferromagnetic (Ga,Mn)As/GaAs Superlattices

The planar Hall effect was used for investigation of magnetic anisotropy in short period (Ca,Mn)As/CaAs superlattices epitaxially grown on (001) oriented GaAs substrate. The results confirmed the existence of low-temperature magneto crystalline anisotropy in the superlattices with the easy magnetic axes directed along the two in-plane (100) directions. Attention is paid to the two-state behaviour of the planar Hall resistance at zero magnetic field that provides its usefulness for applications in non-volatile memory devices