60 research outputs found
Transport characteristics of Pd Schottky barrier diodes on epitaxial n-GaSb as determined from temperature dependent current-voltage measurements
Please read abstract in the article.SA Research Chairs Initiative of the Department of Science and Technology, National Research Foundation and the NMMU.http://www.elsevier.com/locate/tsfhb201
Interface behaviour and electrical performance of ruthenium Schottky contact on 4H-SiC after argon annealing
Rutherford backscattering spectrometry(RBS) analysis , carried out at various annealing temperatures, of a thin
film of ruthenium on n-type 4-hexagonal silicon carbide (4H-SiC) showed evidence of ruthenium oxidation,
ruthenium silicide formation and diffusion of ruthenium into silicon carbide starting from an annealing
temperature of 400oC. Ruthenium oxidation was more pronounced, and ruthenium and Silicon inter-diffusion
was very deep after annealing at 800oC. Raman analysis of some samples also showed ruthenium silicide
formation and oxidation. The Schottky barrier diodes showed very good linear capacitance-voltage
characteristics and excellent forward current-voltage characteristics, despite the occurrence of the chemical
reactions and inter-diffusion of ruthenium and silicon at ruthenium-silicon-carbide interface, up to an annealing
temperature of 800oC.http://link.springer.com/journal/12034hb201
Long range annealing of defects in germanium by low energy plasma ions
Ions arriving at a semiconductor surface with very low energy (2–8 eV) are interacting with defects deep inside the semiconductor. Several different defects were removed or modified in Sb-doped germanium, of which the EE-center has the highest concentration. The low fluence and low energy of the plasma ions imply that the energy has to be able to travel in a localized way to be able to interact with defects up to a few microns below the semiconductor surface. After eliminating other possibilities (electric field, light, heat) we now conclude that moving intrinsic localized modes (ILMs), as a mechanism of long-distance energy transport, are the most likely cause. This would be striking evidence of the importance of ILMs in crystals and opens the way to further experiments to probe ILM properties both in semiconductors and in the metals used for contacts. Although most of the measurements have been performed on germanium, similar effects have been found in silicon.MICINN, project FIS2008-04848; the South African National Research Foundation and the European Regional Development Fund, project 3.2.0101.11-0029, Centre of Excellence Mesosystems: Theory and Applications.http://www.elsevier.com/locate/physdhj201
Comparison of two models for phonon assisted tunneling field enhanced emission from defects in Ge measured by DLTS
Deep Level Transient Spectroscopy (DLTS) was used to measure the field enhanced emission rate from a defect introduced in n-type Ge. The defect was introduced through low energy (±80 eV) inductively coupled plasma (ICP) etching using Ar. The defect, named EP0.31, had an energy level 0.31 eV below the conduction band. Models of Pons and Makram-Ebeid (1979) [2] and Ganichev and Prettl (1997) [3], which describe emission due to phonon assisted tunnelling, were fitted to the observed electric field dependence of the emission rate. The model of Pons and Makram-Ebeid fitted the measured emission rate more accurately the Ganichev and Prettl. However the model of Ganichev and Prettl has only two parameters, while the model of Pons and Makram-Ebeid has four. Both models showed a trasition in the dominant emission mechanism from a weak electron-phonon coupling below 152.5 K to a strong electron –phonon coupling above 155 K. After the application of a x2 goodness of fit test, it was determined that the model of Pons and Makram-Ebeid describes the data well, while that of Ganichev and Prettl does not.The South African National Research Foundationhttp://www.elsevier.com/locate/phys
Temperature-dependent current-voltage characteristics of Pd/ZnO Schottky barrier diodes and the determination of the Richardson constant
We report on a systematic investigation of temperature dependent current-voltage (I-V)
characteristics of Pd/ZnO Schottky barrier diodes in the 30-300 K temperature range. The
ideality factor was observed to decrease with increase in temperature, whilst the barrier
height increases with increase in temperature. The observed trend has been attributed to barrier
inhomogeneities, which results in a distribution of barrier heights at the interface. Using
the dependence of saturation current values on temperature, we have calculated the
Richardson constant (A*) which was investigated in the two distinct temperature regions:
140–200 K and 210–300 K and values 3 x10-12 of and 3x10-9 A cm-2 K-2 were obtained,
respectively. A mean barrier height of 0.97 eV was obtained in the 140-300 K temperature
range. Applying the barrier height inhomogeneities correction, the value of A* was obtained
from the modified Richardson plots as 39.43 and 39.03 A cm-2 K-2 in the 140-200 K and
210-300 K temperature range. The modified Richardson constant (A**) has proved to be
strongly affected by barrier inhomogeneities and dependent on contact quality.South African National Research Foundation (NRF) and the University of Pretoria.http://www.elsevier.com/locate/mssp2016-06-30hb201
Electrical characterisation of electron beam exposure induced defects in silicon
The defects introduced in epitaxially grown p-type silicon (Si) during electron beam exposure were electrically characterised using deep level transient spectroscopy (DLTS) and high resolution Laplace-DLTS. In this process, Si samples were first exposed to the conditions of electron beam deposition (EBD) without metal deposition. This is called electron beam exposure (EBE) herein. After 50 minutes of EBE, nickel (Ni) Schottky contacts were fabricated using the resistive deposition method. The defect level observed using the Ni contacts had an activation energy of H(0.55). This defect has an activation energy similar to that of the I-defect. The defect level is similar to that of the HB4, a boron related defect. DLTS depth profiling revealed that H(0.55) could be detected up to a depth of 0.8 μm below the junction. We found that exposing the samples to EBD conditions without metal deposition introduced a defect which was not introduced by the EBD method. We also observed that the damage caused by EBE extended deeper into the material compared to that caused by EBD.National Research Foundation of South Africa.http://www.elsevier.com/locate/physb2017-01-31hb2016Physic
The fine structure of electron irradiation induced EL2-like defects in n-GaAs
Defects induced by electron irradiation in n-GaAs have been studied using deep level transient spectroscopy
(DLTS) and Laplace DLTS (L-DLTS). The E0.83 (EL2) is the only defect observed prior to
irradiation. Ru/n-GaAs Schottky diodes were irradiated with high energy electrons from a Sr-90 radionuclide
up to a fluence of 2.45 1013 cm 2. The prominent electron irradiation induced defects,
E0.04, E0.14, E0.38, and E0.63, were observed together with the metastable E0.17. Using L-DLTS, we
observed the fine structure of a broad base EL2-like defect peak. This was found to be made up of
the E0.75, E0.83, and E0.85 defects. Our study reveals that high energy electron irradiation increases
the concentration of the E0.83 defect and introduces a family of defects with electronic properties
similar to those of the EL2.The authors gratefully acknowledge the financial
support of the South African National Research Foundation
(NRF) and the University of Pretoria.The South African National Research Foundation
(NRF) and the University of Pretoria.http://scitation.aip.org/content/aip/journal/japam2016Physic
Deep level transient spectroscopy (DLTS) study of defects introduced in antimony doped Ge by 2 MeV proton irradiation
Please read the abstract in the article.The South African National Research Foundation and Monash University, South Africa.http://www.elsevier.com/locate/physbnf201
The effect of high temperatures on the electrical characteristics of Au/n-GaAs Schottky diodes
In this study, the current–voltage (I–V) and capacitance–voltage (C–V) characteristics of Au/n-GaAs Schottky diodes have been measured over a wide temperature range, 80–480 K. The diodes were rectifying throughout the range and showed good thermal stability. Room temperature values for the ideality factor, I–V barrier height and C–V barrier height were found to be n =1.10, ϕIVϕIV=0.85 eV and ϕCVϕCV=0.96 eV, respectively. ϕIVϕIV increases and n decreases with an increase in temperature. We investigated the effect of elevated temperatures on the barrier height and ideality factor by measuring the diodes at a high temperature (annealing mode) then immediately afterwards measuring at room temperature (post annealing mode). The measurements indicate I–V characteristics that degrade permanently above 300 K. Permanent changes to the C–V characteristics were observed only above 400 K. We also noted a discrepancy in the C–V barrier height and carrier concentration between 340 and 400 K, which we attribute to the influence of the EL2 defect (positioned 0.83 eV below the conduction band minima) on the free carrier density. Consequently, we were able to fit the ϕCVϕCV versus temperature curve into two regions with temperature coefficients −6.9×10−4 eV/K and −2.2×10−4 eV/K above and below 400 K.The University of Pretoria and the South African National Research Foundation grant#88021.http://www.journals.elsevier.com/physica-b-condensed-matter2017-01-31hb2016Physic
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