APL Nameplate
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

18 Sep 2000

Volume 77, Issue 12, pp. 1741-1913

Return to All Sections
back to top
RSS Feeds

Very thin insulating layer formed by low-energy Ar-beam bombardment in the surface region of undoped hydrogenated amorphous silicon

R. Durny, E. Pincik, V. Nadazdy, M. Jergel, J. Shimizu, M. Kumeda, and T. Shimizu

Appl. Phys. Lett. 77, 1783 (2000); http://dx.doi.org/10.1063/1.1310634 (3 pages) | Cited 5 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A very thin insulating layer (VTIL) is formed by low-energy Ar-beam bombardment in the surface region of undoped hydrogenated amorphous silicon (a-Si:H). Several experimental techniques have been utilized to determine the optimal argon beam bombardment conditions to prepare electrically reliable VTIL and to investigate its physical properties (thickness, structure, nature, and density of defects). VTILs prepared under such conditions make the leakage current of a-Si:H based semiconductor structures negligible and allow bias voltages of several volts (up to 5 V). © 2000 American Institute of Physics.
Show PACS
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces

Scanning reflection electron microscopy study of surface defects in GaN films formed by epitaxial lateral overgrowth

Heiji Watanabe, Naotaka Kuroda, Haruo Sunakawa, and Akira Usui

Appl. Phys. Lett. 77, 1786 (2000); http://dx.doi.org/10.1063/1.1310631 (3 pages) | Cited 4 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have used scanning reflection electron microscopy (SREM) to detect surface defects in GaN films formed by facet-initiated epitaxial lateral overgrowth. SREM revealed individual threading dislocations and single atomic steps on the GaN surface, and provided images of crystallographic tilting near the surfaces. We found that one of the two tilted GaN crystals in the overgrown areas became dominant and that the surface changed to a single domain after 50-μm-thick GaN deposition. Our SREM results also showed that the deposition of thick (over 100 μm) GaN films significantly improves the crystallographic structures of the overgrown regions, and reduces the threading dislocations in the GaN films. © 2000 American Institute of Physics.
Show PACS
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
68.35.B- Structure of clean surfaces (and surface reconstruction)
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)

Strain-induced material intermixing of InAs quantum dots in GaAs

M. O. Lipinski, H. Schuler, O. G. Schmidt, K. Eberl, and N. Y. Jin-Phillipp

Appl. Phys. Lett. 77, 1789 (2000); http://dx.doi.org/10.1063/1.1311314 (3 pages) | Cited 60 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A systematic investigation of the stacking behavior of InAs quantum dots (QDs) with varying GaAs interlayer thickness d is presented. We compare two-fold stacks of large QDs (≈25 nm base width), which emit at 1.30 μm, to small QDs (≈20 nm base width) emitting at 1.14 μm. For large islands photoluminescence yields an energetic blueshift of the second layer islands with decreasing d, although transmission electron microscopy clearly reveals a ≈70% larger dot size in the second layer, whereas for small islands a similar size increase of the dots in the upper layer and an energetic redshift are observed. A detailed analysis of confinement and material intermixing effects suggests that for large QDs strain driven material intermixing is dominant. For small QDs the confinement effect plays the major role and causes the observed photoluminescence energy redshifts. © 2000 American Institute of Physics.
Show PACS
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
66.30.Ny Chemical interdiffusion; diffusion barriers

Characterizing mechanical resonators by means of a scanning acoustic force microscope

F. Sthal and R. Bourquin

Appl. Phys. Lett. 77, 1792 (2000); http://dx.doi.org/10.1063/1.1311317 (3 pages) | Cited 1 time

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A method of characterizing resonators is presented. This method is based on scanning acoustic force microscopy. Data on the topography and the vibration amplitude of the resonator are obtained simultaneously, by means of atomic force interaction. The normal component of the surface vibration of the resonator is evaluated. A tuning fork resonator and a 10 MHz SC-cut Boîtier Vieillissement Amélioré quartz crystal resonator with adherent electrodes are studied. This analysis allows the cartography of the local characteristics of the resonator material to be made. © 2000 American Institute of Physics.
Show PACS
07.10.-h Mechanical instruments and equipment
07.79.Lh Atomic force microscopes
43.58.Ls Acoustical lenses and microscopes
06.30.Bp Spatial dimensions (e.g., position, lengths, volume, angles, and displacements)
43.35.Yb Ultrasonic instrumentation and measurement techniques

Plasma-induced damage to n-type GaN

H. W. Choi, S. J. Chua, A. Raman, J. S. Pan, and A. T. S. Wee

Appl. Phys. Lett. 77, 1795 (2000); http://dx.doi.org/10.1063/1.1311605 (3 pages) | Cited 34 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The effects of plasma etching on 1/f noise and photoluminescence (PL) characteristics of n-GaN have been investigated. A reduction of 1/f noise was observed after plasma exposure, a result of enhanced passivation of the reactive surface. This is attributed to the removal of carbon and the creation of a Ga-rich surface by the etching process. Nevertheless, the formation of nonradiative recombination centers impaired the PL intensity. Reconstruction of a stoichiometric surface was achieved by annealing. This induced the incorporation of carbon into GaN, deteriorating the PL performance further, but it could be restored by a chemical treatment of 10:1 HF:H2O. © 2000 American Institute of Physics.
Show PACS
81.65.Cf Surface cleaning, etching, patterning
81.05.Ea III-V semiconductors
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
68.35.B- Structure of clean surfaces (and surface reconstruction)

Detection of terahertz radiation from longitudinal optical phonon–plasmon coupling modes in InSb film using an ultrabroadband photoconductive antenna

Ping Gu, Masahiko Tani, Kiyomi Sakai, and T.-R. Yang

Appl. Phys. Lett. 77, 1798 (2000); http://dx.doi.org/10.1063/1.1311609 (3 pages) | Cited 13 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Terahertz radiation from longitudinal optical (LO) phonon–plasmon coupling modes in InSb films is observed using an ultrafast photoconductive antenna detector. We demonstrate a response frequency of up to 7 THz for a low-temperature-grown GaAs-based photoconductive antenna gated with 25 fs laser pulses. It is found that the emission frequencies of the coupling modes are dependent only on the residual carrier density, not on the excitation carrier density. It is also found that the LO phonon–plasmon oscillations in semiconductors can serve as an efficient THz source. © 2000 American Institute of Physics.
Show PACS
63.20.kk Phonon interactions with other quasiparticles
71.45.Gm Exchange, correlation, dielectric and magnetic response functions, plasmons
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors
85.25.Pb Superconducting infrared, submillimeter and millimeter wave detectors
84.40.Ba Antennas: theory, components and accessories
72.30.+q High-frequency effects; plasma effects
72.80.Ey III-V and II-VI semiconductors

Uniaxial locked epitaxy of ZnO on the a face of sapphire

P. Fons, K. Iwata, A. Yamada, K. Matsubara, S. Niki, K. Nakahara, T. Tanabe, and H. Takasu

Appl. Phys. Lett. 77, 1801 (2000); http://dx.doi.org/10.1063/1.1311603 (3 pages) | Cited 81 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
High-quality, c-oriented ZnO epitaxial films have been grown on the a surface using molecular-beam epitaxy. The use of a-oriented sapphire eliminates rotational domains and related structural defects which have limited the use of ZnO in electronic applications. The ZnO epitaxial layers are uniquely oriented with the ZnO/sapphire orientational relationship [0001]‖[11math0] and 〈11math0〉‖[0001]. This unique orientation is a consequence of the anisotropy of the a-sapphire surface in conjunction with a strong correlation along a single direction leading to the term uniaxial locked epitaxy. High-resolution x-ray diffraction measurements show an increase in x-ray lateral coherence length from several tens of nanometers to >0.7 μm for growth of c-oriented ZnO on the a surface as opposed to the c surface of sapphire. © 2000 American Institute of Physics.
Show PACS
81.05.Dz II-VI semiconductors
68.55.-a Thin film structure and morphology
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Two-step growth of high-quality GaN by hydride vapor-phase epitaxy

P. R. Tavernier, E. V. Etzkorn, Y. Wang, and D. R. Clarke

Appl. Phys. Lett. 77, 1804 (2000); http://dx.doi.org/10.1063/1.1311600 (3 pages) | Cited 20 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The use of a low-temperature layer of GaN formed by hydride vapor-phase epitaxy (HVPE) as a template to grow high-quality HVPE films is demonstrated. Using layers formed by reacting GaCl and NH3 at 550 °C and annealed at a growth temperature of 1050 °C, thick films of GaN can be grown by HVPE with fewer than 108 dislocations per cm2. Dislocation densities measured by high-resolution x-ray diffraction, atomic-force microscopy step termination density and plan-view transmission electron miscroscopy reveal that ∼ 23 μm films have dislocation densities of ∼ 6×107 cm−2. Obtaining high-quality single-crystal character films was found to be dependent on several factors, most importantly, the rate of temperature increase to growth temperature and the layer thickness. © 2000 American Institute of Physics.
Show PACS
81.05.Ea III-V semiconductors
68.55.-a Thin film structure and morphology
81.15.Kk Vapor phase epitaxy; growth from vapor phase
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Aligned CNx nanotubes by pyrolysis of ferrocene/C60 under NH3 atmosphere

Wei-Qiang Han, Philipp Kohler-Redlich, Torsten Seeger, Frank Ernst, Manfred Rühle, Nicole Grobert, Wen-Kuang Hsu, Bao-He Chang, Yan-Qiu Zhu, Harold W. Kroto, David R. M. Walton, Mauricio Terrones, and Humberto Terrones

Appl. Phys. Lett. 77, 1807 (2000); http://dx.doi.org/10.1063/1.1311813 (3 pages) | Cited 42 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Aligned CNx (x<0.1) nanotubes have been generated by pyrolyzing ferrocene/C60 mixtures at 1050 °C in an ammonia atmosphere. The structure and composition of the product were determined by high-resolution transmission electron microscopy and high spatial resolution electron energy-loss spectroscopy. The CNx tubes (15–70 nm diameter, <50 μm length) grown in large flakes (<3 mm2) consist of a reduced number of “graphitic” layers (<15 on either side) arranged in a bamboo-like structure. Areas of high nitrogen concentration were found within curved or corrugated “graphite-like” domains. The observation of a well-developed double peak in the σ∗ feature of the N K-edge suggests that the material has not undergone the transition to the fullerene-like phase known for nitrogenated carbons. Incorporation of nitrogen from the gas phase (NH3) into CNx nanotubes therefore leads to improved and more efficient N substitution into the network as compared to the synthesis with solid nitrogen-containing precursors reported earlier. © 2000 American Institute of Physics.
Show PACS
81.05.ub Fullerenes and related materials
61.48.-c Structure of fullerenes and related hollow and planar molecular structures
81.05.Cy Elemental semiconductors
79.20.Kz Other electron-impact emission phenomena
82.30.Lp Decomposition reactions (pyrolysis, dissociation, and fragmentation)

Determination of thermal conductivity of natural silicate melts

R. Büttner, B. Zimanowski, C. Lenk, A. Koopmann, and V. Lorenz

Appl. Phys. Lett. 77, 1810 (2000); http://dx.doi.org/10.1063/1.1311815 (3 pages) | Cited 8 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Cooling of natural silicate melts and energy transfer to the environment are controlled by the temperature-dependent thermal conductivity. We describe a method that allows a correlation between temperature-dependent strain rate and a bulk temperature during a cooling or heating process under quasisteady state conditions in a Newtonian flow regime. A rotational viscometer measured data for experimental cooling curves of remelted volcanic rock materials. From these data we can calculate the thermal conductivity of an unknown melt after we calibrate the setup with a melt of known thermal conductivity as a by-product of viscosimetry. © 2000 American Institute of Physics.
Show PACS
93.85.-q Instruments and techniques for geophysical research: Exploration geophysics
91.60.Ki Thermal properties
83.80.Nb Geological materials: Earth, magma, ice, rocks, etc.
07.20.-n Thermal instruments and apparatus
66.25.+g Thermal conduction in nonmetallic liquids
83.85.Jn Viscosity measurements

Phonons and exciton recombination in CdSe/ZnSe self-assembled quantum dots

H. Rho, L. M. Robinson, L. M. Smith, Howard E. Jackson, S. Lee, M. Dobrowolska, and J. K. Furdyna

Appl. Phys. Lett. 77, 1813 (2000); http://dx.doi.org/10.1063/1.1311393 (3 pages) | Cited 13 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report resonant photoluminescence from CdSe/ZnSe self-assembled quantum dots. When CdSe quantum dots are resonantly excited, excitonic sharp micro-photoluminescence peaks originating from individual quantum dots are strongly enhanced in the region corresponding to optical phonon energies below the excitation. The phonons active in this process are identified as the longitudinal optical (LO) phonons from the CdSe dots, as the interface phonons, and tentatively as the LO phonons from the two-dimensional-like precursor layers. These observations suggest that exciton recombination via phonons is a major relaxation process under resonant excitation. © 2000 American Institute of Physics.
Show PACS
63.22.-m Phonons or vibrational states in low-dimensional structures and nanoscale materials
63.20.kk Phonon interactions with other quasiparticles
78.55.Et II-VI semiconductors
78.66.Hf II-VI semiconductors
68.35.Ja Surface and interface dynamics and vibrations
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
71.35.Gg Exciton-mediated interactions

Room- and low-temperature voltage tunable electroluminescence from a single layer of silicon quantum dots in between two thin SiO2 layers

P. Photopoulos and A. G. Nassiopoulou

Appl. Phys. Lett. 77, 1816 (2000); http://dx.doi.org/10.1063/1.1290603 (3 pages) | Cited 59 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Room- and low-temperature electroluminescence (EL) in the visible range was observed from a single layer of silicon nanocrystals in between two thin SiO2 layers. The EL peak wavelength exhibited tunability from the red (∼800 nm) to the yellow (∼600 nm) depending on the excitation voltage. By decreasing the temperature while keeping the excitation voltage constant, an increase in EL intensity was observed together with a blueshift in EL peak position. This blueshift was much larger than that observed under optical excitation. Nonradiative Auger recombination, Coulomb charging effects, and/or the quantum-confined Stark effect are considered accountable for this behavior. © 2000 American Institute of Physics.
Show PACS
78.66.Db Elemental semiconductors and insulators
78.60.Fi Electroluminescence
78.20.Jq Electro-optical effects

Structural and chemical characterization of free-standing GaN films separated from sapphire substrates by laser lift-off

E. A. Stach, M. Kelsch, E. C. Nelson, W. S. Wong, T. Sands, and N. W. Cheung

Appl. Phys. Lett. 77, 1819 (2000); http://dx.doi.org/10.1063/1.1309030 (3 pages) | Cited 22 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Laser lift-off of GaN heteroepitaxial layers from sapphire substrates is a promising method for electronic device integration and GaN substrate creation. Of critical importance is the structural and chemical quality of the GaN layers following laser processing. In this letter, transmission electron microscopy techniques are used to characterize the modifications that occur at the resulting GaN surfaces. Structural alteration and chemical intermixing following lift-off are confined to approximately the first 50 nm. These results indicate that laser lift-off is a viable route for GaN substrate creation, as well as for electronic device integration. © 2000 American Institute of Physics.
Show PACS
68.55.-a Thin film structure and morphology
42.62.-b Laser applications
81.05.Ea III-V semiconductors
68.35.B- Structure of clean surfaces (and surface reconstruction)
66.30.Ny Chemical interdiffusion; diffusion barriers

Electroluminescence of Ge/Si self-assembled quantum dots grown by chemical vapor deposition

T. Brunhes, P. Boucaud, S. Sauvage, F. Aniel, J.-M. Lourtioz, C. Hernandez, Y. Campidelli, O. Kermarrec, D. Bensahel, G. Faini, and I. Sagnes

Appl. Phys. Lett. 77, 1822 (2000); http://dx.doi.org/10.1063/1.1308526 (3 pages) | Cited 37 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have fabricated light-emitting diodes on Si operating in the near-infrared. The active region of the p–i–n diodes consists of Ge/Si self-assembled quantum dots. The Ge islands were grown in an industrial 200 mm single-wafer chemical vapor deposition reactor. The photoluminescence and the electroluminescence of the islands are resonant in the spectral range around 1.4–1.5 μm wavelength. The electroluminescence is observed up to room temperature. © 2000 American Institute of Physics.
Show PACS
78.60.Fi Electroluminescence
78.66.Db Elemental semiconductors and insulators
85.60.Jb Light-emitting devices
81.05.Cy Elemental semiconductors
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close