Biography:

In the past E. Abramof has collaborated on articles with B. Díaz and A.Y. Ueta. One of their most recent publications is Characterization of Pb0.8Sn0.2Te films grown on KCI substrates by hot-wall epitaxy. Which was published in journal Journal of Crystal Growth.

More information about E. Abramof research including statistics on their citations can be found on their Copernicus Academic profile page.

E. Abramof's Articles: (7)

Characterization of Pb0.8Sn0.2Te films grown on KCI substrates by hot-wall epitaxy

AbstractSingle crystalline Pb0.8Sn0.2Te films were grown on cleaved KC1 substrates by the hot-wall epitaxy technique. Hall concentration and carrier mobility were measured as function of compensation temperature, and the influence of the substrate temperature on layer morphology is studied.

Short period CdTe(ZnTe) /MnTe superlattices: growth and characterization

AbstractWe report on the growth of CdTe /MnTe and ZnTe /MnTe short-period superlattices. The CdTe and ZnTe layers have been grown by atomic layer epitaxy technique, and a quadrupole mass spectrometer controlled molecular beam epitaxy has been used for the MnTe layers growth. The critical thickness of MnTe on both CdTe and ZnTe layers has been determined by reflected high energy electron diffraction experiments and the structure of the superlattices was studied by X-ray diffraction analysis.

Growth of EuTe islands on SnTe by molecular beam epitaxy

AbstractSemiconductor magnetic quantum dots are very promising structures, with novel properties that find multiple applications in spintronic devices. EuTe is a wide gap semiconductor with NaCl structure, and strong magnetic moments S=7/2 at the half filled 4f7 electronic levels. On the other hand, SnTe is a narrow gap semiconductor with the same crystal structure and 4% lattice mismatch with EuTe. In this work, we investigate the molecular beam epitaxial growth of EuTe on SnTe after the critical thickness for island formation is surpassed, as a previous step to the growth of organized magnetic quantum dots. The topology and strain state of EuTe islands were studied as a function of growth temperature and EuTe nominal layer thickness. Reflection high energy electron diffraction (RHEED) was used in-situ to monitor surface morphology and strain state. RHEED results were complemented and enriched with atomic force microscopy and grazing incidence X-ray diffraction measurements made at the XRD2 beamline of the Brazilian Synchrotron. EuTe islands of increasing height and diameter are obtained when the EuTe nominal thickness increases, with higher aspect ratio for the islands grown at lower temperatures. As the islands grow, a relaxation toward the EuTe bulk lattice parameter was observed. The relaxation process was partially reverted by the growth of the SnTe cap layer, vital to protect the EuTe islands from oxidation. A simple model is outlined to describe the distortions caused by the EuTe islands on the SnTe buffer and cap layers. The SnTe cap layers formed interesting plateau structures with easily controlled wall height, that could find applications as a template for future nanostructures growth.

IV–VI Compound heterostructures grown by molecular beam epitaxy

AbstractStructural and optical characterization of some IV–VI superlattices (SL) and multi-quantum wells (MQW) grown by molecular beam epitaxy (MBE) on BaF2 (111) substrates are shown. Three different types of systems were investigated, namely, PbTe/PbSnTe, PbTe/SnTe and PbTe/PbEuTe. High-resolution X-ray diffraction analysis was performed to determine the strain in the structures. The analysis revealed sharp interfaces and good thickness control. The transition energies between the confined levels in the wells were obtained from the absorption steps observed in infrared transmission measurements. Preliminary results on PbTe/Si heterojunction grown by MBE are also presented.

Plasma immersion ion implantation using a glow discharge source with controlled plasma potential

AbstractA DC glow discharge plasma source was used in a plasma immersion ion implantation (PIII) experiment providing nitrogen plasmas with densities of 1–3×1010cm−3 and temperatures of 5–10 eV. Nitrogen ions were extracted from these plasmas and implanted in a variety of immersed samples (Al 5040, SS 304, Si) using repetitive high voltage pulses from two types of sources: PFN pulser and a hard tube pulser. Due to the high potential present in our plasma (350 V), a significant sputter etching of the samples surface occurred at long irradiation times. An electron shower source was used to lower this potential allowing its control from 0 to 350 V. Operating the plasma source at potentials below 70 V reduced the sputtering to negligible levels and a retained dose of 1.5×1017cm−2 was achieved in a silicon surface, after irradiation of 1500 min. For plasma with potential of 350 V (no electron shower), the retained doses in Al 5040 and SS 304 samples were smaller than 5×1016cm−2, for same plasma and pulser conditions (but 2500 min irradiation), confirming the deleterious effects of sputtering measured in Si samples. Upon using the higher repetition rate pulser, the treatment time was reduced by a factor of 700, thus easing considerably the sputtering problem.

Plasma immersion ion implantation experiments at the Instituto Nacional de Pesquisas Espaciais (INPE), Brazil

AbstractHistorical perspective of the development of PIII devices at the Instituto Nacional de Pesquisas Espaciais (INPE) is given, together with the description of the present system under operation and our overall results on this three-dimensional implantation research. Starting with an ignitron switched pulser (1 pulse per 3 min) and an intermittent microwave plasma, we improved our PIII system developing a pulse forming network (PFN) based pulser (20 Hz), 2 years later. We also improved our plasma source towards a DC, highly stable, medium density glow discharge system. A much faster hard tube pulser was recently incorporated to our PIII system (670 Hz) allowing us to achieve good implantation results in different materials. Presently, we are testing a recently purchased RUP-4 commercial pulser to obtain arc prevented, 1.1 kHz, square pulses for new experiments in this active field of PIII research.

Stress study of HFCVD boron-doped diamond films by X-ray diffraction measurements

AbstractStress analysis on chemical vapor deposition (CVD) diamond films has demonstrated an apparent disagreement among various researchers in recent works even for similar deposition conditions. The type and the value of stress have shown a strong dependence on film thickness, which can be attributed to columnar growth and grain size and boundaries. X-Ray diffraction techniques appeared to be more suitable to study these effects and permit the evaluation of the average stress in larger sample areas when compared with micro-Raman spectroscopy, which feels a local strain inside the grains. In the case of boron-doped diamond films, boron incorporation on substitucional or interstitial sites can produce stresses according to the doping level. In order to investigate these effects, a series of diamond films were deposited on silicon (001) substrate in a hot filament (HF)-assisted CVD reactor at 800°C. The CH4 flow is kept at 0.5 sccm for all experiments and the H2 and B2O3/CH3OH/H2 flows are controlled in order to obtain the desired B/C ratios. Stress behavior in HFCVD boron-doped diamond films has been investigated by X-ray diffraction measurements using the sin2 ψ technique. Tensile and compressive stresses have been observed and the thermal and intrinsic components have been calculated. The diamond films were characterized by scanning electron microscopy and Raman spectroscopy.

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