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Hall Measurements (hall + measurement)
Selected AbstractsThe effect of oxygen content on the electrical characteristics of ZnOPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 5 2007E. S. Jung Abstract This work presents the influence of the variation of oxygen content in the ZnO films on their electrical characteristics. We applied the post-thermal annealing in N2 and air ambient to control the oxygen content of ZnO films, which improved crystallinity and optical properties of ZnO films. The oxygen concentration was measured by Auger electron spectroscopy and the electrical characteristics were obtained by Hall measurement in the van der Pauw configuration and transmission line method. As result, it was shown that the electron concentration varies from 1016 to 1021/cm3, while the resistivity from 10,3 to tens ohm-cm with respect to Zn/O concentration ratio. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Effective mass of InN estimated by Raman scatteringPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7-8 2010Jung Gon Kim Abstract We have estimated the longitudinal effective mass (m,) of electron in n-type InN films by Raman scattering. The samples were grown by MOVPE (metal organic vapor phase epitaxy) with free carrier concentration of n =6.7×1018 -9.9×1018 cm -3 according to Hall measurement. A weak Raman signal observed at ,430 cm -1 at room temperature was sharpened and shifted to higher frequency toward the A1(TO)-phonon mode at 447 cm -1 with increasing n. This mode was assigned to the lower branch (L - ) of the longitudinal-optic-phonon-plasmon-coupled (LOPC) mode. The line shape was carefully analyzed by a semi-classical line-shape fitting analysis assuming deformation potential and electro-optic coupling mechanisms for the light scattering process. A line-shape fitting analysis was conducted by adjusting three major parameters; electron density, effective mass and plasmon damping rate. The analysis well reproduced values of electron density and mobility deduced by Hall measurement. Electron effective mass of m,*/m0 = 0.05 (±0.01) was also obtained as the best-fit parameter. The result agrees well with previous data obtained by other optical methods. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Experimental analysis of Mn segregation in Bridgman-grown gallium antimonide: Dependency on the ampoule radiusCRYSTAL RESEARCH AND TECHNOLOGY, Issue 5 2004J. L. Plaza Abstract This work considered the segregation of manganese in vertical Bridgman-grown GaSb crystals for different ampoule diameters. Experimental data of the impurity distribution were obtained from atomic absorption spectrometry and also Hall measurements. It was demonstrated that the radial segregation is more pronounced in the case of thick ampoule diameters. Furthermore the manganese effective segregation coefficient, resistivity, carrier mobility and density were obtained in each case. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Atomistic analysis of B clustering and mobility degradation in highly B-doped junctionsINTERNATIONAL JOURNAL OF NUMERICAL MODELLING: ELECTRONIC NETWORKS, DEVICES AND FIELDS, Issue 4-5 2010Maria Aboy Abstract In this paper we discuss from an atomistic point of view some of the issues involved in the modeling of electrical characteristics evolution in silicon devices as a result of ion implantation and annealing processes in silicon. In particular, evolution of electrically active dose, sheet resistance and hole mobility has been investigated for high B concentration profiles in pre-amorphized Si. For this purpose, Hall measurements combined with atomistic kinetic Monte Carlo atomistic simulations have been performed. An apparent anomalous behavior has been observed for the evolution of the active dose and the sheet resistance, in contrast to opposite trend evolutions reported previously. Our results indicate that this anomalous behavior is due to large variations in hole mobility with active dopant concentration, much larger than that associated to the classical dependence of hole mobility with carrier concentration. Simulations suggest that hole mobility is significantly degraded by the presence of a large concentration of boron-interstitial clusters, indicating the existence of an additional scattering mechanism. Copyright © 2009 John Wiley & Sons, Ltd. [source] Photoluminescence and Hall studies of GaN:Fe and (Ga,Fe)N:Mg layersPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2007M. Wegscheider Abstract Temperature dependent photoluminescence (PL) in the ultraviolet (UV) regime and Hall measurements at room temperature have been performed on Metal-Organic-Chemical-Vapour-Deposition (MOCVD) grown GaN:Fe and (Ga,Fe)N:Mg layers. PL measurements were employed in order to study the dopants' influence on the near-band edge excitonic emission and their tendency to provoke the formation and suppression of defects or incorporation of impurities. For their identification and for the understanding of the PL spectra the evaluation of the free carrier concentrations via Hall measurements were necessary. Depending on the iron concentration of the (Ga,Fe)N layers, the near-band edge emission goes through two different stages: at low Fe-concentration no excitonic emission can be seen whereas with higher doping levels, excitonic features develop. The (Ga,Fe)N films exhibit n-type behaviour. The Mg codoped samples show strong Mg and defect related luminescence bands, whose occurrence and intensity also strongly depends on whether high or low Fe concentration is present. The (Ga,Fe)N:Mg layers were semi insulating. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Low temperature growth of transparent conducting ZnO films by plasma assisted depositionPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 11 2006A. Nishii Abstract Transparent conducting ZnO films are deposited by plasma assisted deposition technique on glass and plastic substrates at temperatures 60 , 300 °C using metallic Zn, metallic Ga and plasma-excited oxygen as source materials. Deposited films were characterized by X-ray diffraction (XRD), optical transmittance in the visible and infrared region, Raman scattering, and Hall measurements. Film properties are controlled by substrate temperature, oxygen source/zinc source supply ratio, and Ga doping. 350 nm-thick Ga-doped ZnO films deposited at 290 °C showed low resistivity (,2 × 10,4 , cm) and high transmittance in the visible region (,85%). (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Effects of oxygen ion implantation in spray-pyrolyzed ZnO thin filmsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 5 2006K. P. Vijayakumar Abstract ZnO thin films, prepared using the chemical spray pyrolysis technique, were implanted using 100 keV O+ ions. Both pristine and ion-implanted samples were characterized using X-ray diffraction, optical absorption, electrical resistivity measurements, thermally stimulated current measurements and photoluminescence. Samples retained their crystallinity even after irradiation at a fluence of ,1015 ions/cm2. However, at a still higher fluence of 2 × 1016 ions/cm2, the films became totally amorphous. The optical absorption edge remained unaffected by implantation and optical absorption spectra indicated two levels at 460 and 510 nm. These were attributed to defect levels corresponding to zinc vacancies (VZn) and oxygen antisites (OZn), respectively. Pristine samples had a broad photoluminescence emission centred at 517 nm, which was depleted on implantation. In the case of implanted samples, two additional emissions appeared at 425 and 590 nm. These levels were identified as due to zinc vacancies (VZn) and oxygen vacancies (VO), respectively. The electrical resistivity of implanted samples was much higher than that of pristine, while photosensitivity decreased to a very low value on implantation. This can be utilized in semiconductor device technology for interdevice isolation. Hall measurements showed a marked decrease in mobility due to ion implantation, while carrier concentration slightly increased. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Electrical properties of InGaN grown by molecular beam epitaxyPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 5 2008William J. Schaff Abstract The electrical properties of InGaN that is either undoped, or Mg doped, are compared to learn about the nature of p-type conductivity. For In alloy fraction beyond 5% Hall measurements do not indicate p-type polarity, even when Mg doping is employed. In contrast, hot probe measurements show that p-polarity can be measured for the entire range of Mg-doped In mole fractions. The conflicting polarity indications are primarily the result of surface electron accumulation. Parasitic surface electron conductivity can further be seen in p,n homojunctions at In fractions including 20% and 30%. This has an impact on structures such as solar cells. Temperature variable conductivity and PL from different layer structures provides further understanding of the nature of InGaN:Mg. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Determination of the mobility ratio in InSb at the temperature of the conductivity type conversionPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 6 2005K. SomogyiArticle first published online: 22 FEB 200 Abstract The temperature dependence of magneto-transport in bulk p-type InSb was investigated, and a special approach was applied for the precise determination of the temperature dependence. Such measurements also allow the determination of the mobility ratio (b) which is known to be large in InSb. Although this type of investigation is standard, in this work an improved method of carrying out temperature-dependent Hall measurements is reported and improved calculations for the determination of large b values in InSb are presented. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Enhancement in electrical properties of GaN heterostructure field-effect transistor by Si atom deposition on AlGaN barrier surfacePHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue S2 2009Norio Onojima Abstract This study demonstrates that deposition of Si atoms on AlGaN barrier surfaces in GaN heterostructure field-effect transistors (HFETs) can modulate the electrical properties of the two-dimensional electron gas (2DEG). The results of Hall measurements performed using the eddy current and four-point van der Pauw methods showed that the sheet resistance of an AlGaN/GaN HFET sample without surface passivation increased from that of the unprocessed sample after post-metallization annealing at 820 °C for ohmic contacts. In contrast, the sheet resistance of the Si-deposited sample did not increase even after annealing. Furthermore, eddy current measurements for unprocessed wafers with and without Si deposition revealed that the sheet resistance can be reduced by depositing Si atoms, regardless of annealing. The effect of Si deposition on devices having a thin Al-rich barrier layer was found to be significant. The deposition of Si atoms (2 nm) on the AlN barrier surface in an AlN/GaN HFET (AlN 2 nm) resulted in a remarkable decrease in the sheet resistance from 60356 to 388 ,/sq. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Influence of barrier thickness on AlInN/AlN/GaN heterostructures and device propertiesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue S2 2009H. Behmenburg Abstract We report on structural and device properties of AlInN/AlN/GaN transistor heterostructures grown by metal organic vapour phase epitaxy (MOVPE) on 2, sapphire substrates with AlInN barriers of thicknesses between 4 nm and 10 nm. The In content and thickness of the thin AlInN barrier is shown to be well determinable by high-resolution X-ray diffraction (HRXRD). Room temperature Hall measurements yielded similar mobility between 1400 cm2V,1s,1 and 1520 cm2V,1s,1 on all samples and increasing sheet carrier concentration ns with rising barrier thickness resulting in a minimum sheet resistance value of 200 Ohm/,. The effect of surface passivation with Si3N4 on the electrical properties is investigated and found to strongly increase sheet carrier concentration ns of the two-dimensional electron gas (2DEG) to values above 2×1013cm,2. Characterization of transistors with gate length Lg of 1.5 ,m produced from the grown samples reveals high transconductance (gm) and a maximum drain current (ID) of 300 mS/mm and ,1 A/mm, respectively. For the sample with 4.6 nm barrier thickness, a reduced gate leakage current (IGL) and a absolute value of the threshold voltage (Vth) of -1.2 V is detected. Radio frequency (RF) measurements of passivated samples lead to maximum current gain cut-off frequencies ft of 11 GHz and maximum oscillating frequencies fmax of 25 GHz. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Deposition of nano-crystalline lead chalcogenide thin films using a simple electrochemical techniquePHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 11 2008Nillohit Mukherjee Abstract Nanocrystalline thin films of lead chalcogenides (PbS, PbSe and PbTe) were deposited on transparent conducting oxide (TCO) coated glass substrates at room temperature using a simple electrochemical (galvanic) technique, from suitable electrolytic solutions and without the application of any external bias. X-ray characterization revealed that PbS, PbSe and PbTe thin films were all of cubic phase. The formation of nanocrystallites with dense and compact surface morphology was detected from FESEM and AFM measurements. The nanocrystalline films showed ,blue shifted' IR absorption. Hall measurements showed the materials to be p-type in nature with carrier concentration in the range 1019 , 1020/cm3. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Transport properties in n-type AlGaN/AlN/GaN-superlatticesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2008J. Hertkorn Abstract In order to improve the lateral conductivity in optoelectronic devices, we have investigated Si-doped AlGaN/AlN/GaN-superlattices. As a first step we performed calculations of the band structure of Al-GaN/AlN/GaN modulation doped multi heterostructures. Based on these results we worked on optimizing the growth of low Al content (xAl, 20%) superlattices by MOVPE. Several tens of abrupt and graded AlGaN/AlN/GaN-layer pairs could be grown crack-free on 2 ,m thick n-GaN layers deposited on sapphire substrates with AlN nucleation. By Van-der-Pauw Hall measurements, we determined that the lateral conductivity of a 1.5 ,m thick superlattice structure is a factor of four higher than in highly n-doped bulk material with comparable thickness without compromising too much the vertical conductivity as confirmed by two step TLM-measurements. At 4K we could demonstrate an extremely high effective mobility of 18760 cm2/Vs at n=2×1014 cm,2 (R=1.6,/®), a clear verification of our excellent crystal quality. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Ce and Yb doped InP layers grown for radiation detectionPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2007J. Zavadil Abstract InP single crystals were grown by liquid phase epitaxy on semi-insulating InP:Fe substrate with cerium (Ce) and ytterbium (Yb) additions to the growth melt. Grown layers were characterised by Hall measurements and low temperature photoluminescence spectroscopy. Both types of layers exhibit the change of electrical conductivity from n to p type. Ce and Yb have been found to be incorporated into the InP lattice since a sharp luminescence lines arising from inner shell transitions of Yb3+ and Ce3+ were detected at 1002 and 3534 nm, respectively. A metastable conductivity state of InP:Ce layers has been found at temperatures below 35 K, a phenomenon previously reported for InP:Yb layers. Similar electrical behaviour of InP (Ce, Yb) layers leads us to conclude that Ce acts as dominant acceptor impurity responsible for n,p conductivity change. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Investigations of p-type signal for ZnO thin films grown on (100) GaAs substrates by pulsed laser depositionPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2006D. J. Rogers Abstract In this work we investigated ZnO films grown on semi-insulating (100) GaAs substrates by pulsed laser deposition. Samples were studied using techniques including X-ray diffraction (XRD), scanning electron microscopy, atomic force microscopy, Raman spectroscopy, temperature dependent photoluminescence, C-V profiling and temperature dependent Hall measurements. The Hall measurements showed a clear p-type response with a relatively high mobility (,260 cm2/V s) and a carrier concentration of ,1.8 × 1019 cm,3. C-V profiling confirmed a p-type response. XRD and Raman spectroscopy indicated the presence of (0002) oriented wurtzite ZnO plus secondary phase(s) including (101) oriented Zn2As2O7. The results suggest that significant atomic mixing was occurring at the film/substrate interface for films grown at substrate temperatures of 450 ºC (without post-annealing). (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Characterisation of the electrical properties of solution-grown GaN crystals by reflectivity and Hall measurementsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3 2006B. Birkmann Abstract By using reflectivity and temperature resolved Hall measurements the electrical properties of low pressure solution grown (LPSG) GaN are determined. Hall measurements show that the material is degenerate. The reflectivity spectra are governed by the free electron gas in accordance with this finding. The charge carrier concentration is about 4 × 1019 cm,3 and the mobility 70 , 80 cm2/V s. These results are compared to gallium nitride synthesized by other solution or vapour phase growth techniques. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Effect of hydrostatic pressure on the transport properties in magnetic semiconductorsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2004M. Csontos Abstract The effect of pressure on the ferromagnetic phase transition has been studied in manganese doped III-V semiconductors by electrical conductance and Hall measurements. We found that the application of hydrostatic pressure shifts the transition temperature upwards both in (In,Mn)Sb and (Ga,Mn)As. The anomalous-Hall coefficient shows a dramatic increase in the hysteresis loops in the ferromagnetic phase and an enhanced magnetization both below and above the phase transition. As the normal-Hall results suggest that the pressure does not change the carrier density [in (In,Mn)Sb] or rather decreases it [in (Ga,Mn)As], all the above observations are indicative of a pressure-induced enhancement of magnetic coupling. [source] Effects of low temperature buffer layer treatments on the growth of high quality ZnO filmsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2004H. Tampo Abstract ZnO films were grown on sapphire substrates by radical source molecular beam epitaxy (RS-MBE). ZnO low temperature buffer layers were subjected to various treatments. High quality ZnO films were obtained by vacuum annealing plus nitrogen doping of the buffer layer. The carrier concentration of the ZnO film fabricated using this buffer layer was 7.5 × 1016 cm,3 with a mobility of 132 cm2/V sec at RT. Temperature dependent Hall measurements showed implied the existence of degenerate (untreated) buffer layers. Using a nitrogen-doped buffer layer to reduce the influence of the degenerate layer, a donor energy of 110 meV was estimated from temperature dependent Hall measurements. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||