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Papers by cloud nyamhere

Research paper thumbnail of Barrier height inhomogeneities on Pd/n-4H-SiC Schottky diodes in a wide temperature range

Materials Science and Engineering: B, 2019

Barrier height inhomogeneities on Pd/n-type 4H-SiC Schottky barrier diodes in the 300-800 K tempe... more Barrier height inhomogeneities on Pd/n-type 4H-SiC Schottky barrier diodes in the 300-800 K temperature range have been investigated. Palladium is known to form silicide above 673 K. Temperature dependent currentvoltage (I-V) characteristics were analyzed. Barrier height (BH) and ideality factor (n) were found to be strongly temperature dependent. Barrier height increased, whilst ideality factor decreased with increasing in temperature and the Richardson plot showed some deviation from linearity. This was attributed to barrier inhomogeneities at the metal-semiconductor interface which resulted in a distribution of barrier heights. From the modified Richardson plot, the modified Richardson constant, A** was found to be 155 Acm −2 K −2 and 87 Acm-2 K −2 in the 300-525 K and the 550-800 K temperature ranges respectively.

Research paper thumbnail of A study of electron induced defects in n-type germanium by deep level transient spectroscopy (DLTS)

physica status solidi (c), 2008

ABSTRACT This paper presents the electrical characteristics of electron irradiation induced defec... more ABSTRACT This paper presents the electrical characteristics of electron irradiation induced defects in n-type germanium doped with antimony (Sb) by deep level transient spectroscopy (DLTS) and Laplace- DLTS. The following electrons traps at 0.15 eV, 0.20 eV, 0.21 eV 0.23 eV, 0.31 eV and 0.38 eV below the conduction band were observed and two hole traps at 0.09 eV and 0.31 eV above the valence band were also recorded. The electron trap level at 0.38 eV is the E – center and is the most dominant electron trap for our measurements. The capacitance versus temperature and current versus temperature characteristics of our samples showed good correlation as the irradiation dose is increased. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Research paper thumbnail of Annealing and surface conduction on Hydrogen peroxide treated bulk melt-grown, single crystal ZnO

Physica B: Condensed Matter, 2012

We report on the studies carried out on hydrogen peroxide treated melt grown, bulk single crystal... more We report on the studies carried out on hydrogen peroxide treated melt grown, bulk single crystal ZnO samples. Results show the existence of two shallow donors in the as-received ZnO samples with energy levels (37.8 ± 0.3) meV that has been suggested as Zn i related and possibly H-complex related and (54.5 ± 0.9) meV which has been assigned to an Al-related donor. Annealing studies performed on the hydrogen peroxide treated samples reveal the existence of a conductive channel in the samples in which new energy levels have been observed, Zn vacancies, related to the Group I elements, X Zn. The surface donor volume concentration of the conductive channel was calculated from theory developed by D. C. Look [1]. Results indicate an increase in surface volume concentration with increasing annealing temperature from 17 6.0 10 cm-3 at 200°C to 18 4.37 10 cm-3 at 800°C.

Research paper thumbnail of Inductively coupled plasma induced deep levels in epitaxial n-GaAs

Physica B: Condensed Matter, 2012

The electronic properties of defects introduced by low energy inductively coupled Ar plasma etchi... more The electronic properties of defects introduced by low energy inductively coupled Ar plasma etching of n-type (Si doped) GaAs were investigated by deeplevel transient spectroscopy (DLTS) and Laplace DLTS. Several prominent electron traps (E c-0.046 eV, E c-0.186 eV, E c-0.314 eV. E c-0.528 eV and E c-0.605 eV) were detected. The metastable defect E c-0.046 eV having a trap signature similar to E1 is observed for the first time. E c-0.314 eV and E c-0.605 eV are metastable and appear to be similar to the M3 and M4 defects present in dc H-plasma exposed GaAs.

Research paper thumbnail of Thermal stability study of palladium and cobalt Schottky contacts on n-Ge (100) and defects introduced during contacts fabrication and annealing process

Physica B: Condensed Matter, 2009

Palladium (Pd) and cobalt (Co) Schottky barrier diodes were fabricated on n-Ge (1 0 0). The Pd-Sc... more Palladium (Pd) and cobalt (Co) Schottky barrier diodes were fabricated on n-Ge (1 0 0). The Pd-Schottky contacts were deposited by resistive evaporation while the Co-contacts were deposited by resistive evaporation and electron beam deposition. Current-voltage (I-V), capacitance-voltage (C-V) and deep level transient spectroscopy (DLTS) measurements were performed on as-deposited and annealed samples. Electrical properties of Pd and Co samples annealed between 30 and 600 1C indicate the formation of one phase of palladium germanide and two phases of cobalt germanide. No defects were observed for the resistively evaporated as-deposited Pd-and Co-Schottky contacts. A hole trap at 0.33 eV above the valence band was observed on the Pd-Schottky contacts after annealing at 300 1C. An electron trap at 0.37 eV below the conduction band and a hole trap at 0.29 eV above the valence band was observed on as-deposited Co-electron beam deposited Schottky contacts. Rutherford back scattering (RBS) technique was also used to characterise the Co-Ge, for as-deposited and annealed samples.

Research paper thumbnail of Characterization of defects introduced in Sb doped Ge by 3keV Ar sputtering using deep level transient spectroscopy (DLTS) and Laplace-DLTS (LDLTS)

Physica B: Condensed Matter, 2009

We have used deep level transient spectroscopy (DLTS), and Laplace-DLTS to investigate the defect... more We have used deep level transient spectroscopy (DLTS), and Laplace-DLTS to investigate the defects created in antimony doped germanium (Ge) by sputtering with 3 keV Ar ions. Hole traps at E V + 0.09 eV and E V + 0.31 eV and an electron trap at E C À 0.38 eV (E-center) were observed soon after the sputtering process. Room temperature annealing of the irradiated samples over a period of a month revealed a hole trap at E V +0.26 eV. Above room temperature annealing studies revealed new hole traps at E V + 0.27 eV, E V +0.30 eV and E V +0.40 eV.

Research paper thumbnail of Analysis of current–voltage measurements on Au/Ni/n-GaN Schottky contacts in a wide temperature range

Materials Science and Engineering: B, 2010

Current-voltage characteristics of Au/Ni/n-GaN Schottky contacts have been measured in the 60-320... more Current-voltage characteristics of Au/Ni/n-GaN Schottky contacts have been measured in the 60-320 K temperature range. The zero bias barrier height, bo  and ideality factor, n have been studied as a function of temperature. The sharp increase in ideality factor at low temperatures has been explained as an effect of thermionic field emission. The deviation of the characteristics from the ideal thermionic behaviour are more pronounced with a decrease in temperature, in which the results obtained indicate the presence of other current transport mechanisms in the 60-280 K temperature range and the dominance of pure thermionic emission current at 300 K. The increase in barrier height with increasing temperature has been explained as an effect of barrier inhomogeneities.

Research paper thumbnail of Correlation Between Barrier Heights and Ideality Factors of Ni/n-Ge (100) Schottky Barrier Diodes

Journal of the Korean Physical Society, 2010

We computed the homogeneous Schottky barrier height (SBH) at ideality factor (n) = 1.0 of Ni/n-Ge... more We computed the homogeneous Schottky barrier height (SBH) at ideality factor (n) = 1.0 of Ni/n-Ge (100) Schottky diodes (SDs). The SDs were identically prepared by using resistive evaporation of Ni on n-Ge (100). The SBHs and n of these diodes (24 dots) were calculated from their experimental forward bias current-voltage (I-V) and reverse bias capacitance-voltage (C-V) measurements at room temperature. Even though the Schottky diodes were identically prepared, the values of the SBH from the I-V characteristics varied from 0.487 to 0.508 eV, the ideality factor varied from 1.34 to 1.53, and the SBH from the C −2-V characteristics varied from 0.358 to 0.418 eV. The Gaussian fits of the experimental SBH distributions obtained from the C −2-V and the I-V characteristics yielded mean SBH values of 0.401 ± 0.015 and 0.503 ± 0.006 eV, respectively. Furthermore, a homogeneous SBH value of approximately 0.535 eV was also computed from an extrapolation of a linear plot of the experimental SBHs versus the ideality factors. The homogeneous SBHs, rather than the effective SBHs, of individual contacts or mean values should be used to discuss the theories and the physical mechanisms that determine the SBHs of SDs.

Research paper thumbnail of Electrical characterization of defects introduced in n-GaAs by alpha and beta irradiation from radionuclides

Applied Physics A Solids and Surfaces, 1993

We investigated defect production in n-type GaAs with two different free-carrier densities (4×101... more We investigated defect production in n-type GaAs with two different free-carrier densities (4×1014 and 1×1016/cm3) by using particles liberated from radionuclides. 90Sr and 241Am were employed as beta and alpha sources, respectively. The results obtained for electron irradiation showed that the same set of primary defects can be produced by beta irradiation from the Sr source as by electrons produced

Research paper thumbnail of Deep level transient spectroscopy (DLTS) study of defects introduced in antimony doped Ge by 2MeV proton irradiation

Physica B: Condensed Matter, 2011

Deep level transient spectroscopy (DLTS), and Laplace-DLTS have been used to investigate the defe... more Deep level transient spectroscopy (DLTS), and Laplace-DLTS have been used to investigate the defects created in Sb doped Ge after irradiation with 2 MeV protons having a fluence of 1 x 10 13 protons/cm 2. The results show that proton irradiation resulted in primary hole traps at E V + 0.15 eV and E V + 0.30 eV and electron traps, at E C-0.38 eV, E C-0.32 eV, E C-0. 31 eV, E C-0.22 eV, E C-0.20 eV, E C-0.17 eV, E C-0.15 eV and E C-0.04 eV. Defects observed in this study are compared with those introduced in similar samples after MeV electron irradiation reported earlier. E C-0.31 eV, E C-0.17 eV and, E C-0.04 eV, and E V + 0.15 eV were not observed previously in similar samples after high energy irradiation. Results from this study suggest that although similar defects are introduced by electron and proton irradiation, traps introduced by the latter are dose dependent.

Research paper thumbnail of Remote Poultry Management System for Small to Medium Scale Producers Using IoT

Research paper thumbnail of Electrical characterization of ruthenium Schottky contacts on nGe ( 100 )

Ruthenium (Ru) Schottky contacts were fabricated on n-Ge (100) by electron beam deposition. Curre... more Ruthenium (Ru) Schottky contacts were fabricated on n-Ge (100) by electron beam deposition. Current–voltage (I-V), deep level transient spectroscopy (DLTS), and Laplace-DLTS techniques were used to characterize as-deposited and annealed Ru/nGe (100) Schottky contacts. The variation of electrical properties of Ru samples annealed between 25C and 575C indicate the formation of two phases of ruthenium germanide. After Ru Schottky contacts fabrication, an electron trap at 0.38 eV below the conduction band with capture cross section of 1.0 × 10 cm is the only detectable electron trap. The hole traps at 0.09, 0.15, 0.27 and 0.30 eV above the valence band with capture cross sections 7.8 × 10 cm, 7.1 × 10 cm, 2.4 × 10 cm, and 6.2 × 10 cm, respectively were observed in as-deposited Ru Schottky contacts. The hole trap H(0.30) is the prominent single acceptor level of the E-centre, and H(0.09) is the third charge state of the E-centre. H(0.27) shows some reverse annealing and reaches maximum c...

Research paper thumbnail of Comparison of nickel, cobalt, pelladium and tungsten schottky contacts on n-4H-SiC

Research paper thumbnail of Comparison of nickel, cobalt, palladium, and tungsten Schottky contacts on n-4 H -silicon carbide

Physica B: Condensed Matter, 2017

We have investigated the current-voltage (I-V) characteristics of nickel (Ni), cobalt (Co), tungs... more We have investigated the current-voltage (I-V) characteristics of nickel (Ni), cobalt (Co), tungsten (W) and palladium (Pd) Schottky contacts on n-type 4H-SiC in the 300-800 K temperature range. Results extracted from I-V measurements of Schottky barrier diodes showed that barrier height (Ф Bo) and ideality factor (n) were strongly dependent on temperature. Schottky barrier heights for contacts of all the metals showed an increase with temperature between 300 K and 800 K.

Research paper thumbnail of Thermal Stability of Ti/Mo Schottky Contacts on p-Si and Defects Introduced in p-Si during Electron Beam Deposition of Ti/Mo

Solid State Phenomena, 2005

In this study we have investigated the thermal stability (in the range 100 oC - 900 oC) of defect... more In this study we have investigated the thermal stability (in the range 100 oC - 900 oC) of defects introduced in p-Si by electron beam deposition (EBD) of Ti and Ti/Mo Schottky contacts. The depletion regions below these contacts were probed by conventional deep level transient spectroscopy (DLTS) as well as Laplace (high-resolution) DLTS (L-DLTS). We have chosen Ti as the Schottky contact because the barrier height of Ti/p-Si (0.53 eV) is close to that of TiSi2/p-Si (0.50 eV) that forms after annealing at 600 – 650 oC. The Mo was added on top of the Ti in order to prevent annealing degradation. These contacts were annealed in Ar at temperatures of up to 900 oC in 100 oC steps for half-hour periods. Current – voltage (I-V) and capacitance – voltage (C-V) measurements were used to monitor the quality of the Schottky contacts. DLTS was performed after each annealing cycle to monitor the presence of the EBD-induced defects and to obtain heir electronic properties. We have found that th...

Research paper thumbnail of Characterization of defects created in Cz and epitaxial Si doped with Ga or B using Laplace-DLTS

Physica B: Condensed Matter, 2006

We have measured the electrical and annealing properties of defects created in epitaxial and Czoc... more We have measured the electrical and annealing properties of defects created in epitaxial and Czochralski-grown Si doped with either B or Ga by electron irradiation using both conventional and Laplace deep level transient spectroscopy (L)-DLTS. With L-DLTS, we have been able to resolve several defects that cannot be resolved using conventional DLTS. L-DLTS provides a new avenue to study defect introduction rates and annealing kinetics in Band Ga-doped Si. The isochronal annealing behaviour of the defects was also investigated.

Research paper thumbnail of Experimental Observation of Intrinsic Localized Modes in Germanium

Springer Series in Materials Science, 2015

Deep level transient spectroscopy shows that defects created by alpha irradiation of germanium ar... more Deep level transient spectroscopy shows that defects created by alpha irradiation of germanium are annealed by low energy plasma ions up to a depth of several thousand lattice units. The plasma ions have energies of 2-8 eV and therefore can deliver energies of the order of a few eV to the germanium atoms. The most abundant defect is identified as the E-center, a complex of the dopant antimony and a vacancy with and annealing energy of 1.3 eV as determined by our measurements. The inductively coupled plasma has a very low density and a very low flux of ions. This implies that the ion impacts are almost isolated both in time and at the surface of the semiconductor. We conclude that energy of the order of an eV is able to travel a large distance in germanium in a localized way and is delivered to the defects effectively. The most likely candidates are vibrational nonlinear wave packets known as intrinsic localized modes, which exist for a limited range of energies. This property is coherent with the fact that more energetic ions are less efficient at producing the annealing effect.

Research paper thumbnail of Electrical characterization of {311} defects and related junction leakage currents in n-type Si after ion implantation

AIP Conference Proceedings, 2012

A special fabrication process involving chemical vapor deposition (CVD) was designed in order to ... more A special fabrication process involving chemical vapor deposition (CVD) was designed in order to fabricate advanced structures used to successfully investigate both deep level transient spectroscopy (DLTS) and leakage currents related to the defects on the same test structures. Silicon ions of energy 160 keV and doses 1.0 × 1012 cm−2, 1.0 × 1013 cm−2 and 8.0 × 1013 cm−2 have been implanted into n-type Si substrate and annealed at 800°C. The highest dose was specifically used to create rod-like {311} extended defects. DLTS spectra show prominent electron traps at EC - 0.26 eV, EC - 0.46 eV and EC - 0.54 eV. There were no observable deep levels in the un-implanted (reference) samples. The identity and origin of all these traps will be interpreted in conjunction with annealing studies, literature results and recently developed predictive defect simulation models. The junction leakage current is found to slightly increase in the presence of {311} defects, which shows that their presence does not significantly...

Research paper thumbnail of Electrical and optical characterization of extended defects induced in p-type Si after Si ion implantation

physica status solidi (c), 2013

Research paper thumbnail of Comparison of metal Schottky contacts on n‐Ge (100) at different annealing temperatures

physica status solidi c, 2010

... Study of the solid state reaction between the metal films and germanium to deter-mine the pha... more ... Study of the solid state reaction between the metal films and germanium to deter-mine the phase formation sequence [5,9,11,13,15,17], mi-crostructure of material [9,10,12], growth kinetics[11,16] and electrical ... [17] SP Ashburn, MC Öztürk, G. Harris ... [19] http://ece-www.colorado ...

Research paper thumbnail of Barrier height inhomogeneities on Pd/n-4H-SiC Schottky diodes in a wide temperature range

Materials Science and Engineering: B, 2019

Barrier height inhomogeneities on Pd/n-type 4H-SiC Schottky barrier diodes in the 300-800 K tempe... more Barrier height inhomogeneities on Pd/n-type 4H-SiC Schottky barrier diodes in the 300-800 K temperature range have been investigated. Palladium is known to form silicide above 673 K. Temperature dependent currentvoltage (I-V) characteristics were analyzed. Barrier height (BH) and ideality factor (n) were found to be strongly temperature dependent. Barrier height increased, whilst ideality factor decreased with increasing in temperature and the Richardson plot showed some deviation from linearity. This was attributed to barrier inhomogeneities at the metal-semiconductor interface which resulted in a distribution of barrier heights. From the modified Richardson plot, the modified Richardson constant, A** was found to be 155 Acm −2 K −2 and 87 Acm-2 K −2 in the 300-525 K and the 550-800 K temperature ranges respectively.

Research paper thumbnail of A study of electron induced defects in n-type germanium by deep level transient spectroscopy (DLTS)

physica status solidi (c), 2008

ABSTRACT This paper presents the electrical characteristics of electron irradiation induced defec... more ABSTRACT This paper presents the electrical characteristics of electron irradiation induced defects in n-type germanium doped with antimony (Sb) by deep level transient spectroscopy (DLTS) and Laplace- DLTS. The following electrons traps at 0.15 eV, 0.20 eV, 0.21 eV 0.23 eV, 0.31 eV and 0.38 eV below the conduction band were observed and two hole traps at 0.09 eV and 0.31 eV above the valence band were also recorded. The electron trap level at 0.38 eV is the E – center and is the most dominant electron trap for our measurements. The capacitance versus temperature and current versus temperature characteristics of our samples showed good correlation as the irradiation dose is increased. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Research paper thumbnail of Annealing and surface conduction on Hydrogen peroxide treated bulk melt-grown, single crystal ZnO

Physica B: Condensed Matter, 2012

We report on the studies carried out on hydrogen peroxide treated melt grown, bulk single crystal... more We report on the studies carried out on hydrogen peroxide treated melt grown, bulk single crystal ZnO samples. Results show the existence of two shallow donors in the as-received ZnO samples with energy levels (37.8 ± 0.3) meV that has been suggested as Zn i related and possibly H-complex related and (54.5 ± 0.9) meV which has been assigned to an Al-related donor. Annealing studies performed on the hydrogen peroxide treated samples reveal the existence of a conductive channel in the samples in which new energy levels have been observed, Zn vacancies, related to the Group I elements, X Zn. The surface donor volume concentration of the conductive channel was calculated from theory developed by D. C. Look [1]. Results indicate an increase in surface volume concentration with increasing annealing temperature from 17 6.0 10 cm-3 at 200°C to 18 4.37 10 cm-3 at 800°C.

Research paper thumbnail of Inductively coupled plasma induced deep levels in epitaxial n-GaAs

Physica B: Condensed Matter, 2012

The electronic properties of defects introduced by low energy inductively coupled Ar plasma etchi... more The electronic properties of defects introduced by low energy inductively coupled Ar plasma etching of n-type (Si doped) GaAs were investigated by deeplevel transient spectroscopy (DLTS) and Laplace DLTS. Several prominent electron traps (E c-0.046 eV, E c-0.186 eV, E c-0.314 eV. E c-0.528 eV and E c-0.605 eV) were detected. The metastable defect E c-0.046 eV having a trap signature similar to E1 is observed for the first time. E c-0.314 eV and E c-0.605 eV are metastable and appear to be similar to the M3 and M4 defects present in dc H-plasma exposed GaAs.

Research paper thumbnail of Thermal stability study of palladium and cobalt Schottky contacts on n-Ge (100) and defects introduced during contacts fabrication and annealing process

Physica B: Condensed Matter, 2009

Palladium (Pd) and cobalt (Co) Schottky barrier diodes were fabricated on n-Ge (1 0 0). The Pd-Sc... more Palladium (Pd) and cobalt (Co) Schottky barrier diodes were fabricated on n-Ge (1 0 0). The Pd-Schottky contacts were deposited by resistive evaporation while the Co-contacts were deposited by resistive evaporation and electron beam deposition. Current-voltage (I-V), capacitance-voltage (C-V) and deep level transient spectroscopy (DLTS) measurements were performed on as-deposited and annealed samples. Electrical properties of Pd and Co samples annealed between 30 and 600 1C indicate the formation of one phase of palladium germanide and two phases of cobalt germanide. No defects were observed for the resistively evaporated as-deposited Pd-and Co-Schottky contacts. A hole trap at 0.33 eV above the valence band was observed on the Pd-Schottky contacts after annealing at 300 1C. An electron trap at 0.37 eV below the conduction band and a hole trap at 0.29 eV above the valence band was observed on as-deposited Co-electron beam deposited Schottky contacts. Rutherford back scattering (RBS) technique was also used to characterise the Co-Ge, for as-deposited and annealed samples.

Research paper thumbnail of Characterization of defects introduced in Sb doped Ge by 3keV Ar sputtering using deep level transient spectroscopy (DLTS) and Laplace-DLTS (LDLTS)

Physica B: Condensed Matter, 2009

We have used deep level transient spectroscopy (DLTS), and Laplace-DLTS to investigate the defect... more We have used deep level transient spectroscopy (DLTS), and Laplace-DLTS to investigate the defects created in antimony doped germanium (Ge) by sputtering with 3 keV Ar ions. Hole traps at E V + 0.09 eV and E V + 0.31 eV and an electron trap at E C À 0.38 eV (E-center) were observed soon after the sputtering process. Room temperature annealing of the irradiated samples over a period of a month revealed a hole trap at E V +0.26 eV. Above room temperature annealing studies revealed new hole traps at E V + 0.27 eV, E V +0.30 eV and E V +0.40 eV.

Research paper thumbnail of Analysis of current–voltage measurements on Au/Ni/n-GaN Schottky contacts in a wide temperature range

Materials Science and Engineering: B, 2010

Current-voltage characteristics of Au/Ni/n-GaN Schottky contacts have been measured in the 60-320... more Current-voltage characteristics of Au/Ni/n-GaN Schottky contacts have been measured in the 60-320 K temperature range. The zero bias barrier height, bo  and ideality factor, n have been studied as a function of temperature. The sharp increase in ideality factor at low temperatures has been explained as an effect of thermionic field emission. The deviation of the characteristics from the ideal thermionic behaviour are more pronounced with a decrease in temperature, in which the results obtained indicate the presence of other current transport mechanisms in the 60-280 K temperature range and the dominance of pure thermionic emission current at 300 K. The increase in barrier height with increasing temperature has been explained as an effect of barrier inhomogeneities.

Research paper thumbnail of Correlation Between Barrier Heights and Ideality Factors of Ni/n-Ge (100) Schottky Barrier Diodes

Journal of the Korean Physical Society, 2010

We computed the homogeneous Schottky barrier height (SBH) at ideality factor (n) = 1.0 of Ni/n-Ge... more We computed the homogeneous Schottky barrier height (SBH) at ideality factor (n) = 1.0 of Ni/n-Ge (100) Schottky diodes (SDs). The SDs were identically prepared by using resistive evaporation of Ni on n-Ge (100). The SBHs and n of these diodes (24 dots) were calculated from their experimental forward bias current-voltage (I-V) and reverse bias capacitance-voltage (C-V) measurements at room temperature. Even though the Schottky diodes were identically prepared, the values of the SBH from the I-V characteristics varied from 0.487 to 0.508 eV, the ideality factor varied from 1.34 to 1.53, and the SBH from the C −2-V characteristics varied from 0.358 to 0.418 eV. The Gaussian fits of the experimental SBH distributions obtained from the C −2-V and the I-V characteristics yielded mean SBH values of 0.401 ± 0.015 and 0.503 ± 0.006 eV, respectively. Furthermore, a homogeneous SBH value of approximately 0.535 eV was also computed from an extrapolation of a linear plot of the experimental SBHs versus the ideality factors. The homogeneous SBHs, rather than the effective SBHs, of individual contacts or mean values should be used to discuss the theories and the physical mechanisms that determine the SBHs of SDs.

Research paper thumbnail of Electrical characterization of defects introduced in n-GaAs by alpha and beta irradiation from radionuclides

Applied Physics A Solids and Surfaces, 1993

We investigated defect production in n-type GaAs with two different free-carrier densities (4×101... more We investigated defect production in n-type GaAs with two different free-carrier densities (4×1014 and 1×1016/cm3) by using particles liberated from radionuclides. 90Sr and 241Am were employed as beta and alpha sources, respectively. The results obtained for electron irradiation showed that the same set of primary defects can be produced by beta irradiation from the Sr source as by electrons produced

Research paper thumbnail of Deep level transient spectroscopy (DLTS) study of defects introduced in antimony doped Ge by 2MeV proton irradiation

Physica B: Condensed Matter, 2011

Deep level transient spectroscopy (DLTS), and Laplace-DLTS have been used to investigate the defe... more Deep level transient spectroscopy (DLTS), and Laplace-DLTS have been used to investigate the defects created in Sb doped Ge after irradiation with 2 MeV protons having a fluence of 1 x 10 13 protons/cm 2. The results show that proton irradiation resulted in primary hole traps at E V + 0.15 eV and E V + 0.30 eV and electron traps, at E C-0.38 eV, E C-0.32 eV, E C-0. 31 eV, E C-0.22 eV, E C-0.20 eV, E C-0.17 eV, E C-0.15 eV and E C-0.04 eV. Defects observed in this study are compared with those introduced in similar samples after MeV electron irradiation reported earlier. E C-0.31 eV, E C-0.17 eV and, E C-0.04 eV, and E V + 0.15 eV were not observed previously in similar samples after high energy irradiation. Results from this study suggest that although similar defects are introduced by electron and proton irradiation, traps introduced by the latter are dose dependent.

Research paper thumbnail of Remote Poultry Management System for Small to Medium Scale Producers Using IoT

Research paper thumbnail of Electrical characterization of ruthenium Schottky contacts on nGe ( 100 )

Ruthenium (Ru) Schottky contacts were fabricated on n-Ge (100) by electron beam deposition. Curre... more Ruthenium (Ru) Schottky contacts were fabricated on n-Ge (100) by electron beam deposition. Current–voltage (I-V), deep level transient spectroscopy (DLTS), and Laplace-DLTS techniques were used to characterize as-deposited and annealed Ru/nGe (100) Schottky contacts. The variation of electrical properties of Ru samples annealed between 25C and 575C indicate the formation of two phases of ruthenium germanide. After Ru Schottky contacts fabrication, an electron trap at 0.38 eV below the conduction band with capture cross section of 1.0 × 10 cm is the only detectable electron trap. The hole traps at 0.09, 0.15, 0.27 and 0.30 eV above the valence band with capture cross sections 7.8 × 10 cm, 7.1 × 10 cm, 2.4 × 10 cm, and 6.2 × 10 cm, respectively were observed in as-deposited Ru Schottky contacts. The hole trap H(0.30) is the prominent single acceptor level of the E-centre, and H(0.09) is the third charge state of the E-centre. H(0.27) shows some reverse annealing and reaches maximum c...

Research paper thumbnail of Comparison of nickel, cobalt, pelladium and tungsten schottky contacts on n-4H-SiC

Research paper thumbnail of Comparison of nickel, cobalt, palladium, and tungsten Schottky contacts on n-4 H -silicon carbide

Physica B: Condensed Matter, 2017

We have investigated the current-voltage (I-V) characteristics of nickel (Ni), cobalt (Co), tungs... more We have investigated the current-voltage (I-V) characteristics of nickel (Ni), cobalt (Co), tungsten (W) and palladium (Pd) Schottky contacts on n-type 4H-SiC in the 300-800 K temperature range. Results extracted from I-V measurements of Schottky barrier diodes showed that barrier height (Ф Bo) and ideality factor (n) were strongly dependent on temperature. Schottky barrier heights for contacts of all the metals showed an increase with temperature between 300 K and 800 K.

Research paper thumbnail of Thermal Stability of Ti/Mo Schottky Contacts on p-Si and Defects Introduced in p-Si during Electron Beam Deposition of Ti/Mo

Solid State Phenomena, 2005

In this study we have investigated the thermal stability (in the range 100 oC - 900 oC) of defect... more In this study we have investigated the thermal stability (in the range 100 oC - 900 oC) of defects introduced in p-Si by electron beam deposition (EBD) of Ti and Ti/Mo Schottky contacts. The depletion regions below these contacts were probed by conventional deep level transient spectroscopy (DLTS) as well as Laplace (high-resolution) DLTS (L-DLTS). We have chosen Ti as the Schottky contact because the barrier height of Ti/p-Si (0.53 eV) is close to that of TiSi2/p-Si (0.50 eV) that forms after annealing at 600 – 650 oC. The Mo was added on top of the Ti in order to prevent annealing degradation. These contacts were annealed in Ar at temperatures of up to 900 oC in 100 oC steps for half-hour periods. Current – voltage (I-V) and capacitance – voltage (C-V) measurements were used to monitor the quality of the Schottky contacts. DLTS was performed after each annealing cycle to monitor the presence of the EBD-induced defects and to obtain heir electronic properties. We have found that th...

Research paper thumbnail of Characterization of defects created in Cz and epitaxial Si doped with Ga or B using Laplace-DLTS

Physica B: Condensed Matter, 2006

We have measured the electrical and annealing properties of defects created in epitaxial and Czoc... more We have measured the electrical and annealing properties of defects created in epitaxial and Czochralski-grown Si doped with either B or Ga by electron irradiation using both conventional and Laplace deep level transient spectroscopy (L)-DLTS. With L-DLTS, we have been able to resolve several defects that cannot be resolved using conventional DLTS. L-DLTS provides a new avenue to study defect introduction rates and annealing kinetics in Band Ga-doped Si. The isochronal annealing behaviour of the defects was also investigated.

Research paper thumbnail of Experimental Observation of Intrinsic Localized Modes in Germanium

Springer Series in Materials Science, 2015

Deep level transient spectroscopy shows that defects created by alpha irradiation of germanium ar... more Deep level transient spectroscopy shows that defects created by alpha irradiation of germanium are annealed by low energy plasma ions up to a depth of several thousand lattice units. The plasma ions have energies of 2-8 eV and therefore can deliver energies of the order of a few eV to the germanium atoms. The most abundant defect is identified as the E-center, a complex of the dopant antimony and a vacancy with and annealing energy of 1.3 eV as determined by our measurements. The inductively coupled plasma has a very low density and a very low flux of ions. This implies that the ion impacts are almost isolated both in time and at the surface of the semiconductor. We conclude that energy of the order of an eV is able to travel a large distance in germanium in a localized way and is delivered to the defects effectively. The most likely candidates are vibrational nonlinear wave packets known as intrinsic localized modes, which exist for a limited range of energies. This property is coherent with the fact that more energetic ions are less efficient at producing the annealing effect.

Research paper thumbnail of Electrical characterization of {311} defects and related junction leakage currents in n-type Si after ion implantation

AIP Conference Proceedings, 2012

A special fabrication process involving chemical vapor deposition (CVD) was designed in order to ... more A special fabrication process involving chemical vapor deposition (CVD) was designed in order to fabricate advanced structures used to successfully investigate both deep level transient spectroscopy (DLTS) and leakage currents related to the defects on the same test structures. Silicon ions of energy 160 keV and doses 1.0 × 1012 cm−2, 1.0 × 1013 cm−2 and 8.0 × 1013 cm−2 have been implanted into n-type Si substrate and annealed at 800°C. The highest dose was specifically used to create rod-like {311} extended defects. DLTS spectra show prominent electron traps at EC - 0.26 eV, EC - 0.46 eV and EC - 0.54 eV. There were no observable deep levels in the un-implanted (reference) samples. The identity and origin of all these traps will be interpreted in conjunction with annealing studies, literature results and recently developed predictive defect simulation models. The junction leakage current is found to slightly increase in the presence of {311} defects, which shows that their presence does not significantly...

Research paper thumbnail of Electrical and optical characterization of extended defects induced in p-type Si after Si ion implantation

physica status solidi (c), 2013

Research paper thumbnail of Comparison of metal Schottky contacts on n‐Ge (100) at different annealing temperatures

physica status solidi c, 2010

... Study of the solid state reaction between the metal films and germanium to deter-mine the pha... more ... Study of the solid state reaction between the metal films and germanium to deter-mine the phase formation sequence [5,9,11,13,15,17], mi-crostructure of material [9,10,12], growth kinetics[11,16] and electrical ... [17] SP Ashburn, MC Öztürk, G. Harris ... [19] http://ece-www.colorado ...