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23 Sep 2002

Volume 81, Issue 13, pp. 2319-2480

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Thermoelectric properties of Bi2Sr2Co2O9 whiskers under hydrostatic pressure

F. Chen, K. L. Stokes, and Ryoji Funahashi

Appl. Phys. Lett. 81, 2379 (2002); http://dx.doi.org/10.1063/1.1510160 (3 pages) | Cited 3 times

Online Publication Date: 16 September 2002

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We report the temperature dependence of thermopower (S) in the ab plane of Bi2Sr2Co2O9 (BC-222) single crystalline whiskers under high pressure up to 1.2 GPa. Special modifications were made to our high-pressure transport measurement system to improve the measurement accuracy of S for whiskers with high resistance. Pressure improved the contact resistance dramatically. We observed a slight decrease of S and four-wire electrical conductivity (σ) under high pressure. As a result, the power factor (S2σ) was decreased less than 20% by pressure. From the temperature dependence of σ, the band gap of BC-222 whiskers increase very slightly under high pressure. © 2002 American Institute of Physics.
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72.15.Nj Collective modes (e.g., in one-dimensional conductors)
72.15.Jf Thermoelectric and thermomagnetic effects
62.50.-p High-pressure effects in solids and liquids
73.40.Cg Contact resistance, contact potential

Surface Fermi-level position and gap state distribution of InGaP surface grown by metalorganic vapor-phase epitaxy

Tamotsu Hashizume

Appl. Phys. Lett. 81, 2382 (2002); http://dx.doi.org/10.1063/1.1509119 (3 pages) | Cited 2 times

Online Publication Date: 16 September 2002

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Electronic properties of “free” n-In0.49Ga0.51P surfaces grown by metalorganic vapor-phase epitaxy were directly characterized using the contactless capacitance–voltage technique. The HCl-treated surface showed a wide and continuous distribution of surface state density (Dss) in energy with relatively low densities, leading to no pronounced Fermi-level pinning effect on the surface. The minimum Dss value was determined to be 8×1011 cm−2 eV−1. The surface Fermi-level position was found at 1.2 eV above the valence band maximum, consistent with the x-ray photoelectron spectroscopy results. © 2002 American Institute of Physics.
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73.20.At Surface states, band structure, electron density of states
81.05.Ea III-V semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
79.60.Bm Clean metal, semiconductor, and insulator surfaces
81.65.Cf Surface cleaning, etching, patterning

High energy proton irradiation effects on SiC Schottky rectifiers

S. Nigam, Jihyun Kim, F. Ren, G. Y. Chung, M. F. MacMillan, R. Dwivedi, T. N. Fogarty, R. Wilkins, K. K. Allums, C. R. Abernathy, S. J. Pearton, and J. R. Williams

Appl. Phys. Lett. 81, 2385 (2002); http://dx.doi.org/10.1063/1.1509468 (3 pages) | Cited 18 times

Online Publication Date: 16 September 2002

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4H-SiC Schottky rectifiers with dielectric overlap edge termination were exposed to 40 MeV protons at fluences from 5×107–5×109 cm−2. The reverse breakdown voltage decreased from ∼ 500 V in unirradiated devices to ∼ −450 V after the highest proton dose. The reverse leakage current at −250 V was approximately doubled under these conditions. The forward current at −2 V decreased by ∼ 1% (fluence of 5×107 cm−2) to ∼ 42% (fluence of 5×109 cm−2), while the current at lower biases was increased due to the introduction of defect centers. The ideality factor, on-state resistance, and forward turn-on voltage showed modest increases for fluences of ⩽ 5×108 cm−2, but were more strongly affected (increase of 40%–75%) at the highest dose employed. © 2002 American Institute of Physics.
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73.40.Ei Rectification
73.30.+y Surface double layers, Schottky barriers, and work functions
61.80.Jh Ion radiation effects
73.40.Ns Metal-nonmetal contacts
61.82.Fk Semiconductors

Control of grain-boundary tunneling barriers in polycrystalline silicon

Toshio Kamiya, Zahid A. K. Durrani, and Haroon Ahmed

Appl. Phys. Lett. 81, 2388 (2002); http://dx.doi.org/10.1063/1.1509853 (3 pages) | Cited 8 times

Online Publication Date: 16 September 2002

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The effect of oxidation and annealing on the electrical properties of grain boundaries (GBs) in heavily doped polycrystalline silicon is characterized using bulk films and 30-nm-wide nanowires. Oxidation at 650–750 °C selectively oxidizes the GBs. Subsequent annealing at 1000 °C increases the associated potential barrier height and resistance. These observations can be explained by structural changes in the Si–O network at the GBs and the competition between surface oxygen diffusion and oxidation from the GBs in the crystalline grains. A combination of oxidation and annealing may provide a method that can better control the GB potential barriers. © 2002 American Institute of Physics.
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73.40.Gk Tunneling
72.80.Cw Elemental semiconductors
61.72.Mm Grain and twin boundaries
61.72.Cc Kinetics of defect formation and annealing
81.65.Mq Oxidation

Improved theory for remote-charge-scattering-limited mobility in metal–oxide–semiconductor transistors

Shin-ichi Saito, Kazuyoshi Torii, Masahiko Hiratani, and Takahiro Onai

Appl. Phys. Lett. 81, 2391 (2002); http://dx.doi.org/10.1063/1.1510178 (3 pages) | Cited 22 times

Online Publication Date: 16 September 2002

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Transport theory is extended to include the remote-charge-scattering-limited electron mobility of metal–oxide–semiconductor field-effect transistors. We evaluated remote-charge-scattering from the depletion charge in the polycrystalline silicon gate. We obtained an analytical expression for the scattering potential, by taking image charge, screening, and quantization effects into account. The potential increases with decreasing gate-oxide thickness, which results in a mobility degradation at lower vertical electric fields. The calculated mobility agrees well with recent measurements. © 2002 American Institute of Physics.
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85.30.Tv Field effect devices
85.30.De Semiconductor-device characterization, design, and modeling

Study of photocurrent characteristics in PbSrSe thin films for infrared detection

H. F. Yang, W. Z. Shen, and Q. J. Pang

Appl. Phys. Lett. 81, 2394 (2002); http://dx.doi.org/10.1063/1.1509474 (3 pages) | Cited 4 times

Online Publication Date: 16 September 2002

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We have carried out a detailed investigation of photocurrent spectra in Pb1−xSrxSe thin films grown by molecular-beam epitaxy on BaF2 substrates with Sr composition from 0.066 to 0.276 under different temperatures from 77 to 300 K. Strong room temperature infrared detection has been demonstrated with the wavelength from 1.0 to 3.1 μm. By employing a diffusion-recombination model to analyze the temperature- and Sr composition-dependent photocurrent, we find that the photocurrent in the investigated PbSrSe thin films is dominated by bulk excitation, recombination, and transport processes. For the application of infrared detection, the optimal thickness for PbSrSe thin films should be less than 2.5 μm. © 2002 American Institute of Physics.
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07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors
85.60.Gz Photodetectors (including infrared and CCD detectors)
72.40.+w Photoconduction and photovoltaic effects
73.50.Pz Photoconduction and photovoltaic effects
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
73.61.Ng Insulators

Hydrogen redistribution induced by negative-bias-temperature stress in metal–oxide–silicon diodes

Ziyuan Liu, Shinji Fujieda, Koichi Terashima, Markus Wilde, and Katsuyuki Fukutani

Appl. Phys. Lett. 81, 2397 (2002); http://dx.doi.org/10.1063/1.1508809 (3 pages) | Cited 4 times

Online Publication Date: 16 September 2002

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Poly-Si/SiO2/Si diodes in which oxides were grown thermally under wet oxidation conditions and subsequently treated by a post-oxidation anneal (POA) have been characterized electrically and chemically before and after applying negative-bias-temperature stress (NBTS). It was confirmed that NBTS produces interface states and that POA suppresses the interface state production. Nuclear reaction analysis indicated that NBTS results in hydrogen redistribution within the oxide layer. POA was shown to partly suppress such hydrogen accumulation. Hydrogen is thus clearly shown to influence the stability against NBTS. © 2002 American Institute of Physics.
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85.30.Kk Junction diodes
85.30.De Semiconductor-device characterization, design, and modeling
73.40.Ty Semiconductor-insulator-semiconductor structures
61.72.S- Impurities in crystals
81.65.Mq Oxidation
81.40.Gh Other heat and thermomechanical treatments
73.20.-r Electron states at surfaces and interfaces
68.35.Ct Interface structure and roughness

Energy level alignment at organic/metal interfaces: Dipole and ionization potential

H. Peisert, M. Knupfer, and J. Fink

Appl. Phys. Lett. 81, 2400 (2002); http://dx.doi.org/10.1063/1.1509472 (3 pages) | Cited 65 times

Online Publication Date: 16 September 2002

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We present a systematic study of the energy level alignment at the interfaces between gold and organic semiconductors. It is shown that there are at least two leading contributions to the potential drop (dipole) across the metal/organic interface: A modification of the metal work function due to the adsorption of the organic molecules and a potential change in the organic semiconductor. © 2002 American Institute of Physics.
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73.20.Hb Impurity and defect levels; energy states of adsorbed species
73.30.+y Surface double layers, Schottky barriers, and work functions

Semimetal–semiconductor transition in Bi1−xSbx alloy nanowires and their thermoelectric properties

Yu-Ming Lin, O. Rabin, S. B. Cronin, Jackie Y. Ying, and M. S. Dresselhaus

Appl. Phys. Lett. 81, 2403 (2002); http://dx.doi.org/10.1063/1.1503873 (3 pages) | Cited 51 times

Online Publication Date: 16 September 2002

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The resistivity of Bi1−xSbx nanowire arrays exhibits complex variations as a function of Sb content x and temperature T due to the unique semimetal-to-semiconductor (SM–SC) transition experienced by the nanowires. Seebeck coefficient measurements show enhanced thermopower due to Sb alloying and the reduction in wire diameter. The theoretical model not only explains these transport measurements, but also suggests a useful technique to experimentally determine (i) whether the wire is semimetallic or semiconducting, (ii) the carrier concentration, and (iii) the conditions for the SM–SC transition. © 2002 American Institute of Physics.
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73.63.Bd Nanocrystalline materials
72.60.+g Mixed conductivity and conductivity transitions
61.46.-w Structure of nanoscale materials
72.15.Jf Thermoelectric and thermomagnetic effects
72.20.Pa Thermoelectric and thermomagnetic effects
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