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19 Mar 2001

Volume 78, Issue 12, pp. 1649-1795

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Broadband semiconductor superlattice detector for THz radiation

F. Klappenberger, A. A. Ignatov, S. Winnerl, E. Schomburg, W. Wegscheider, K. F. Renk, and M. Bichler

Appl. Phys. Lett. 78, 1673 (2001); http://dx.doi.org/10.1063/1.1352669 (3 pages) | Cited 12 times

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We report on a broadband GaAs/AlAs superlattice detector for THz radiation; a THz field reduces the current through a superlattice, which is carried by miniband electrons, due to modulation of the Bloch oscillations of the miniband electrons. We studied the detector response, by use of a free electron laser, in a large frequency range (5–12 THz). The responsivity showed strong minima at frequencies of infrared active phonons of the superlattice. A theoretical analysis of the detector delivers an understanding of the role of phonons and gives a characterization of the responsivity. © 2001 American Institute of Physics.
Show PACS
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
63.22.-m Phonons or vibrational states in low-dimensional structures and nanoscale materials
41.60.Cr Free-electron lasers
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors
85.25.Pb Superconducting infrared, submillimeter and millimeter wave detectors

Sb-doped SrTiO3 transparent semiconductor thin films

H. H. Wang, F. Chen, S. Y. Dai, T. Zhao, H. B. Lu, D. F. Cui, Y. L. Zhou, Z. H. Chen, and G. Z. Yang

Appl. Phys. Lett. 78, 1676 (2001); http://dx.doi.org/10.1063/1.1355992 (3 pages) | Cited 19 times

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Optically transparent Sb-doped SrTiO3 thin films with a transmittance higher than 95% in most of the visible region have been grown on SrTiO3 (001) substrate by pulsed laser deposition. The films behave as an n-type semiconductor between 10 K and room temperature. The carrier concentration and mobility of the films at room temperature are ∼ 5.8×1017 cm−3 and ∼ 6.4 cm2/V s, respectively. X-ray photoelectron spectroscopy measurement reveals that the delocalized electrons from the Sb dopants give rise to deep impurity levels within the band gap of the parent compound, which are responsible for the electrical conduction observed. The wide band gap and low density of states in the conduction band account for transparency of the films. © 2001 American Institute of Physics.
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81.05.Hd Other semiconductors
81.15.Fg Pulsed laser ablation deposition
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
73.50.Dn Low-field transport and mobility; piezoresistance
79.60.Bm Clean metal, semiconductor, and insulator surfaces
78.66.Li Other semiconductors
78.40.Ha Other nonmetallic inorganics

Hydrogen depth-profiling in chemical-vapor-deposited diamond films by high-resolution elastic recoil detection

Kenji Kimura, Kaoru Nakajima, Sadanori Yamanaka, Masataka Hasegawa, and Hideyo Okushi

Appl. Phys. Lett. 78, 1679 (2001); http://dx.doi.org/10.1063/1.1356452 (3 pages) | Cited 15 times

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We have measured the hydrogen depth profiles in chemical-vapor-deposited diamond films by elastic recoil detection. Depth resolution of ∼ 0.23 nm is achieved using a high-resolution magnetic spectrometer. The hydrogen depth profile shows a sharp peak at surface, and the hydrogen coverage is estimated to be 1±0.3 ML, indicating formation of the monohydride structure. The surface peak has a small tail toward deeper region, which is ascribed to hydrogen atoms incorporated in a subsurface region. These subsurface hydrogen atoms might be the origin of the surface conductivity. © 2001 American Institute of Physics.
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68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
61.72.up Other materials
81.05.U- Carbon/carbon-based materials
81.05.Cy Elemental semiconductors

Electrical characterization of TiN/a-C/Si devices grown by magnetron sputtering at room temperature

N. Konofaos, C. T. Angelis, E. K. Evangelou, Y. Panayiotatos, C. A. Dimitriadis, and S. Logothetidis

Appl. Phys. Lett. 78, 1682 (2001); http://dx.doi.org/10.1063/1.1352658 (3 pages) | Cited 6 times

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Amorphous carbon (α-C) films were deposited on Si substrates by magnetron sputtering at room temperature, followed by a deposition of TiN on top of the carbon films to form heterojunction devices. The electrical properties of the TiN/α–C/Si devices were characterized by capacitance–voltage, conductance–voltage, and current–voltage measurements as a function of temperature. The results showed that the devices behaved like metal–insulator–semiconductor devices at low temperatures, while at higher temperatures, the carbon films exhibited a high internal conductivity and the overall performance was similar to that of heterojunction devices. The conductivity was adequately modeled and found to follow the thermionic field emission model. The TiN exhibited an excellent behavior as a metallic electrode of the devices. © 2001 American Institute of Physics.
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73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
81.05.U- Carbon/carbon-based materials
81.15.Cd Deposition by sputtering
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)

Inhomogeneous spatial distribution of reverse bias leakage in GaN Schottky diodes

J. W. P. Hsu, M. J. Manfra, D. V. Lang, S. Richter, S. N. G. Chu, A. M. Sergent, R. N. Kleiman, L. N. Pfeiffer, and R. J. Molnar

Appl. Phys. Lett. 78, 1685 (2001); http://dx.doi.org/10.1063/1.1356450 (3 pages) | Cited 115 times

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The reverse bias leakage current in macroscopic GaN Schottky diodes is found to be insensitive to barrier height. Using a scanning current–voltage microscope, we show that the reverse bias current occurs at small isolated regions, while most of the sample is insulating. By comparing the current maps to topographic images and transmission electron microscopy results, we conclude that reverse bias leakage occurs primarily at dislocations with a screw component. Furthermore, for a fixed dislocation density, the V/III ratio during the molecular beam epitaxial growth strongly affects reverse leakage, indicating complex dislocation electrical behavior that is sensitive to the local structural and/or chemical changes. © 2001 American Institute of Physics.
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85.30.Kk Junction diodes
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
81.05.Ea III-V semiconductors
68.37.-d Microscopy of surfaces, interfaces, and thin films
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)

Photoluminescence and electrical characteristics of the two-dimensional electron gas in Si delta-doped GaN layers

C. W. Teng, M. O. Aboelfotoh, R. F. Davis, J. F. Muth, and R. M. Kolbas

Appl. Phys. Lett. 78, 1688 (2001); http://dx.doi.org/10.1063/1.1353836 (3 pages) | Cited 2 times

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We have studied the electrical and photoluminescence (PL) properties of a Si delta-doped GaN layer grown by metalorganic chemical vapor deposition. The Hall mobility and electron sheet concentration are 726 cm2/V s and 1.9×1012 cm−2, respectively, at 2 K. A PL peak located at 78 meV below the band gap of GaN is observed at 77 K. This PL peak is attributed to the radiative recombination between electrons in the two-dimensional quantum states and photoexcited holes in GaN, which is consistent with simulation results using a one-dimensional Poisson and Schrödinger equation solver. The peak disappears at temperatures higher than 77 K and is not observed in uniformly doped GaN layers. © 2001 American Institute of Physics.
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78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
73.61.Ey III-V semiconductors
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
72.20.My Galvanomagnetic and other magnetotransport effects

Effect of low-temperature annealing on transport and magnetism of diluted magnetic semiconductor (Ga, Mn)As

Takashi Hayashi, Yoshiaki Hashimoto, Shingo Katsumoto, and Yasuhiro Iye

Appl. Phys. Lett. 78, 1691 (2001); http://dx.doi.org/10.1063/1.1352701 (3 pages) | Cited 12 times

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We report improvements in the crystallinity of a III–V-based diluted magnetic semiconductor (Ga, Mn)As by heat treatment (annealing) after growth at comparatively low temperatures. This method can be used to raise the Curie temperature to 100 K without the need for severe optimization of growth conditions, as well as to adjust the material parameters to desired values. © 2001 American Institute of Physics.
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81.40.Rs Electrical and magnetic properties related to treatment conditions
75.50.Pp Magnetic semiconductors
81.40.Gh Other heat and thermomechanical treatments
61.72.Cc Kinetics of defect formation and annealing
75.50.Dd Nonmetallic ferromagnetic materials
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
61.66.Fn Inorganic compounds

Characterization of defects in doped InGaAsN grown by molecular-beam epitaxy

A. Fleck, B. J. Robinson, and D. A. Thompson

Appl. Phys. Lett. 78, 1694 (2001); http://dx.doi.org/10.1063/1.1355011 (3 pages) | Cited 12 times

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Defects in doped InGaAsN ( ≈ 1.5% N) grown by gas source molecular-beam epitaxy are examined through Hall effect measurements. The behavior of the carrier concentration as a function of N content and doping concentration is examined. A Fermi statistics model based upon the experimental results has identified the energy levels and concentrations of three traps in as-grown InGaAsN. © 2001 American Institute of Physics.
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71.55.Eq III-V semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
81.05.Ea III-V semiconductors

Si/SiGe/Si:Er:O light-emitting transistors prepared by differential molecular-beam epitaxy

Chun-Xia Du, Fabrice Duteil, Göran V. Hansson, and Wei-Xin Ni

Appl. Phys. Lett. 78, 1697 (2001); http://dx.doi.org/10.1063/1.1356732 (3 pages) | Cited 4 times

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Si/SiGe/Si:Er:O heterojunction bipolar transistor (HBT) type light-emitting devices with Er3+ ions incorporated in the collector region have been fabricated using a layered structure grown by differential molecular-beam epitaxy. Electroluminescence measurements on processed light-emitting HBTs can be performed in either constant driving current mode or constant applied bias mode, which is an important advantage over conventional Si:Er light-emitting diodes. Intense room-temperature light emission at the Er3+ characteristic wavelength of 1.54 μm has been observed at low driving current density, e.g., 0.1 A cm−2, and low applied bias, e.g., 3 V, across the collector and emitter. © 2001 American Institute of Physics.
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85.60.Jb Light-emitting devices
78.60.Fi Electroluminescence
78.66.Db Elemental semiconductors and insulators
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
85.30.Pq Bipolar transistors

Electrical activation of carbon in GaAs: Implantation temperature effects

I. Danilov, J. P. de Souza, A. V. Murel, and M. A. A. Pudenzi

Appl. Phys. Lett. 78, 1700 (2001); http://dx.doi.org/10.1063/1.1356729 (3 pages) | Cited 2 times

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Carbon was implanted into GaAs at the energy of 1 MeV with doses between 1×1013 and 2×1015 cm−2 at temperatures of 80 K, nominal room temperature (RT), and 300 °C. A markedly higher electrical activation was obtained in the samples implanted at 80 K compared to those implanted at RT or 300 °C, attaining a maximum hole concentration of 2×1019 cm−3. The redistribution of the C profile during rapid thermal annealing at temperatures from 700 to 950 °C for 10 s was found negligible, independently of the implantation temperature. Similar improvements in the electrical properties were also verified in samples implanted at 80 K with a lower energy of 60 keV. We consider that despite the light mass of C ions, the reduced dynamic annealing at 80 K allows the accumulation of an abundance of As vacancies, which assist the C activation as a p-type dopant. © 2001 American Institute of Physics.
Show PACS
71.55.Eq III-V semiconductors
61.72.uj III-V and II-VI semiconductors
61.72.Cc Kinetics of defect formation and annealing
72.20.Fr Low-field transport and mobility; piezoresistance
61.72.Yx Interaction between different crystal defects; gettering effect

Electronic structure and conduction in a metal–semiconductor digital composite: ErAs:InGaAs

D. C. Driscoll, M. Hanson, C. Kadow, and A. C. Gossard

Appl. Phys. Lett. 78, 1703 (2001); http://dx.doi.org/10.1063/1.1355988 (3 pages) | Cited 32 times

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We have grown epitaxial superlattice structures of layers of semimetallic ErAs particles embedded in an InGaAs matrix on (001) Fe-doped InP substrates. Temperature-dependent Hall measurements, x-ray diffraction, and transmission electron microscopy were performed on the materials. The carrier mobility and the temperature dependence of the charge density imply conduction in the InGaAs matrix. We calculate an offset between the conduction-band minimum of the InGaAs matrix and the Fermi level of the ErAs particles that is strongly dependent on the amount of ErAs deposited. As the size of the ErAs particles increases, the Fermi level decreases from ∼0.01 eV above the InGaAs conduction-band edge to ∼0.2 eV below the InGaAs conduction-band edge and the electrical conduction properties change from metallic to semiconducting. © 2001 American Institute of Physics.
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73.21.Cd Superlattices
73.63.-b Electronic transport in nanoscale materials and structures
72.20.My Galvanomagnetic and other magnetotransport effects
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