Role of growth mode in the formation of magnetic properties of InMnAs grown by MOVPE (original) (raw)
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Study of the growth and structural properties of InMnAs dots grown on high-index surfaces by MOVPE
Materials Science in Semiconductor Processing, 2010
The growth of InMnAs quantum dots by low pressure MOVPE technique on patterned (1 0 0) GaAs substrates was studied. The patterning in the form of ridges with sidewalls having (2 1 1) and (3 1 1) facets was prepared by wet chemical etching via a GaAs/AlAs sacrificial etching mask structure. AFM studies showed that the dots formation and distribution were very similar for both types of facets under study. InMnAs dot density on the (3 1 1) plane is about 5-7 times lower in comparison to that on the (1 0 0) planar substrate. The dots on sidewalls are larger in comparison to average dots formatted on planar GaAs (1 0 0) substrate. The lateral dimensions of these dots are in the interval 100-180 nm. In addition, dot distribution along the sidewall (from top to bottom) is not uniform. A higher dot concentration was observed close to the intersection of (3 1 1) facets with concave bottom part of the valleys between ridges. Finally, no dots were grown on the (1 0 0) plane created by self-faceting on the top of the triangular ridges. This is probably a consequence of the high quality of the (1 0 0) facet formed by lateral overgrowth.
Room-temperature ferromagnetic behaviour of InMnAs films grown by laser ablation technique
Journal of Physics: Conference Series, 2010
InMnAs layers were fabricated by pulsed laser ablation of solid targets (Mn and InAs) in flow of hydrogen and arsine. The InMnAs layers with thickness ranging from 130 to 270 nm were deposited on semi-insulating GaAs (100) substrates at 320ºC. The Mn quantity was controlled by changing ratio of sputtering time of Mn and InAs targets. The X-ray diffraction measurements identified the InMnAs as mosaic monocrystal with MnAs phase texture inclusions. Room temperature ferromagnetism of these InMnAs layers is evident from magnetometry and magneto-optical measurements. In addition, the InMnAs layers show anomalous Hall effect with the hysteresis loop and saturation magnetic field H S ≈ 2500 Oe at temperatures up to 300K depending on the Mn content. The Curie temperature higher than 300K allows using these magnetic semiconductor layers as a source of spin polarized carriers in room temperature spintronic devices.
Dependence of Curie temperature on surface strain in InMnAs epitaxial structures
Applied Surface Science, 2010
Pairs of self-assembled InMnAs quantum dot structures and reference epitaxial layers (0 < x < 0.13) were prepared on GaAs substrates by low-pressure metal organic vapour phase epitaxy. Magnetic moment measurements indicated that reference epitaxial layer had a Curie temperature of 343 K independent on the composition. On the other hand, the quantum dots prepared under Stranski-Krastanov growth mode from the identical gas phase composition showed a lower value of Curie temperature. This value varied from 41 to 235 K in relation to the material composition. Moiré fringes at transmission electron microscopy plan view were used for characterization of strain in InMnAs quantum dot structures.
Design, preparation and properties of spin-LED structures based on InMnAs
The Eighth International Conference on Advanced Semiconductor Devices and Microsystems, 2010
Great advances in the development of III-V diluted magnetic semiconductors materials (DMS) allow for the incorporation of ferromagnetic epitaxial layers into advanced structures. In this contribution, we report on the growth of GaAs/InMnAs layers by metalorganic vapour phase epitaxy (MOVPE) over an AlGaAs/GaAs MQW light-emitting diode structure. In particular, results of electrical and structural characterization of structures are presented. We prepared a single-phase ferromagnetic In 1-x Mn x As ternary with x close to 0.075 on (100) GaAs substrates using MOVPE. The material exhibited room temperature ferromagnetic behavior with a Curie temperature close to 330K. In addition, all InMnAs ternary samples showed p-type conductivity. The ferromagnetic material was incorporated into four different AlGaAs/GaAs LED structure.
Mn-doped InAs self-organized diluted magnetic quantum-dot layers with Curie temperatures above 300 K
Applied Physics Letters, 2004
The magnetic and structural properties of InAs:Mn self-organized diluted magnetic quantum dots grown by low-temperature ͑ϳ270°C͒, solid-source molecular-beam epitaxy using a very low InAs growth rate ͑Ͻ0.1 ML/ s͒ are investigated. A Curie temperature ͑T C ͒ of ϳ350 K is measured in a sample grown with a Mn/ In flux ratio of 0.15. Electron energy-loss spectroscopy confirms that most of the Mn remains within the InAs quantum dots. We propose as a possible explanation for this high T C the effects of magnetic and structural disorder introduced by a random incorporation and inhomogeneous distribution of Mn atoms amongst the InAs quantum dots.
MOVPE growth and properties of light emitting diodes with an incorporated InMnAs ferromagnetic layer
Journal of Crystal Growth, 2011
AlGaAs/GaAs light emitting diode (LED) structures with an InMnAs ferromagnetic layer were grown by metal organic vapour phase epitaxy. Four different LED structures were studied. Their electroluminescence spectra revealed one peak at an energy of 1.467 eV in accordance with the design of the active quantum-well (QW) region. The incorporation of a 100 nm thick InMnAs layer into one of the LED structures led to a 50% decrease in the total optical output power of the LEDs compared with that of LEDs based on the QW structure that did not have InMnAs (reference structure). LEDs based on the structures with InMnAs exhibited dark currents between 1 mA and 1 mA at V R ¼ À5 V. Those based on the reference LED structure had a dark current of 20 nA. Temperature dependent magnetic measurements proved that the LED structures with InMnAs were ferromagnetic at room temperature.
Applied Physics Letters, 1996
Thermal properties of the hybrid graphene-metal nano-micro-composites: Applications in thermal interface materials Appl. Phys. Lett. 100, 073113 Efficiently recyclable magnetic core-shell photocatalyst for photocatalytic oxidation of chlorophenol in water J. Appl. Phys. 111, 07B504 Enhancing and broadening absorption properties of frequency selective surfaces absorbers using FeCoB-based thin film J. Appl. Phys. 111, 07E703 Template-based synthesis and magnetic properties of Mn-Zn ferrite nanotube and nanowire arrays
Journal of Magnetism and Magnetic Materials, 2018
We report the influence of the Mn atomic concentration (at.%) on the nanostructures formation and magnetic properties of GaAs:Mn layers grown by Molecular Beam Epitaxy at a relatively high substrate temperature of 530°C varying the nominal Mn at.% content from 0.01 to 0.2. It is shown that by modifying the Mn at.% different kind of nanostructures, ranging from 2D (such as islands and surface corrugation) to 3D microleaveand nanowire-like arrays, form on the surface layer. Samples produced with Mn contents ranging from 0.02 to 0.20 at.% show a significant room temperature ferromagnetic response that is attributed to the formation of MnAs nanocrystals as confirmed from X-ray diffraction analysis and magnetization measurements. The influence of MnAs clusters on the formation of the nanostructures observed is discussed.