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17 Jun 2002

Volume 80, Issue 24, pp. 4483-4665

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Laser diode structure for the generation of high-power picosecond optical pulses

Sergey Vainshtein, Juha Kostamovaara, Larisa Shestak, Mikhail Sverdlov, and Vladimir Tretyakov

Appl. Phys. Lett. 80, 4483 (2002); http://dx.doi.org/10.1063/1.1486478 (3 pages) | Cited 6 times

Online Publication Date: 10 June 2002

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A laser diode structure is designed and tested that permits the generation of high-power ( ∼ 100 W) picosecond-range optical pulses. Direct current pumping is used with a current pulse duration of a few nanoseconds and a current amplitude of ∼ 105 A/cm2. The main distinguishing feature of the structure is separation of the electron injector (p–n junction) from the active region by a potential barrier. The optical gain in the active region is controlled by the transverse electric field, which is determined by the magnitude of the current at each instant. The design allows emission wavelength control by means of band gap engineering. © 2002 American Institute of Physics.
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42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.55.Px Semiconductor lasers; laser diodes
42.60.Fc Modulation, tuning, and mode locking
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.60.By Design of specific laser systems

Dye-doped polymers for blue organic diode lasers

María A. Díaz-García, Susana Fernández De Ávila, and Mark G. Kuzyk

Appl. Phys. Lett. 80, 4486 (2002); http://dx.doi.org/10.1063/1.1485303 (3 pages) | Cited 17 times

Online Publication Date: 10 June 2002

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Amplified spontaneous emission (ASE) in optically pumped polymeric films containing the luminescent and hole-transporting organic molecule N,N′-Bis(3-methylphenyl)-N,N′diphenylbenzidine (TPD) is demonstrated. ASE is observed in polymer films of polystyrene and poly(N-vinylcarbazole) doped up to 20% with TPD. From these results, we conclude that TPD-based films are candidates for blue-emitting organic diode lasers. © 2002 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
78.66.Qn Polymers; organic compounds
78.45.+h Stimulated emission
42.60.By Design of specific laser systems
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation

On-chain defect emission in electroluminescent polyfluorenes

J. M. Lupton, M. R. Craig, and E. W. Meijer

Appl. Phys. Lett. 80, 4489 (2002); http://dx.doi.org/10.1063/1.1486482 (3 pages) | Cited 93 times

Online Publication Date: 10 June 2002

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We present time-resolved photoluminescence measurements on a range of poly- and oligofluorenes with different molecular weights in both dilute solution and thin films. The commonly observed parasitic broad green emission band, which has previously been attributed to an excimer, is identified in all solution and film samples and assigned to an on-chain emissive defect. By comparison of the luminescence decay in the solid state at different temperatures it is shown that, at room temperature, intramolecular relaxation is faster in these polyphenylenes than intermolecular exciton diffusion. © 2002 American Institute of Physics.
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78.55.Kz Solid organic materials
78.55.Bq Liquids
71.55.Jv Disordered structures; amorphous and glassy solids
36.20.Cw Molecular weights, dispersity
78.60.Fi Electroluminescence
36.20.Kd Electronic structure and spectra
78.47.-p Spectroscopy of solid state dynamics
78.66.Qn Polymers; organic compounds

Parametric fluorescence in periodically poled LiNbO3 buried waveguides

Katia Gallo, Marc De Micheli, and Pascal Baldi

Appl. Phys. Lett. 80, 4492 (2002); http://dx.doi.org/10.1063/1.1486265 (3 pages) | Cited 11 times

Online Publication Date: 10 June 2002

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We report on the periodic poling of LiNbO3 buried waveguides fabricated by reverse proton exchange. We evaluate their linear and nonlinear quadratic properties with the aid of parametric fluorescence. © 2002 American Institute of Physics.
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42.79.Gn Optical waveguides and couplers
42.65.Wi Nonlinear waveguides
81.05.Mh Cermets, ceramic and refractory composites
78.55.Hx Other solid inorganic materials
78.60.-b Other luminescence and radiative recombination
77.22.Ej Polarization and depolarization

Photonic band schemes of opals composed of periodic arrays of cored spheres depending on thickness of outer shells

Hiroyuki Takeda and Katsumi Yoshino

Appl. Phys. Lett. 80, 4495 (2002); http://dx.doi.org/10.1063/1.1487448 (3 pages) | Cited 11 times

Online Publication Date: 10 June 2002

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Photonic band schemes of opals as pseudophotonic crystals composed of three-dimensional arrays of cored spheres are calculated theoretically. Pseudophotonic band gaps are confirmed to be dependent on the thickness of outer shells and also refractive indices of the inner core and outer shells. Tunabilities of photonic band schemes of these types of opals are also discussed. © 2002 American Institute of Physics.
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42.70.Qs Photonic bandgap materials
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
71.20.Ps Other inorganic compounds

Tunable photonic strength in porous GaP

J. Gómez Rivas, A. Lagendijk, R. W. Tjerkstra, D. Vanmaekelbergh, and J. J. Kelly

Appl. Phys. Lett. 80, 4498 (2002); http://dx.doi.org/10.1063/1.1485316 (3 pages) | Cited 20 times

Online Publication Date: 10 June 2002

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The light-scattering properties of porous gallium phosphide, prepared by electrochemical etching, are investigated. We show that the photonic strength of the porous semiconductor can be tuned from weak to extremely strong. This tunability is related to the density and size of the pores, which are controlled by the dopant density of the GaP crystals, and the etching potential. Moreover, electrochemical etching does not introduce any significant optical absorption, which makes porous GaP suitable for many photonic applications. © 2002 American Institute of Physics.
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42.70.Qs Photonic bandgap materials
81.05.Rm Porous materials; granular materials
81.65.Cf Surface cleaning, etching, patterning
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Probing confined interfacial excitations in buried layers by Brillouin light scattering

X. Zhang and R. Sooryakumar

Appl. Phys. Lett. 80, 4501 (2002); http://dx.doi.org/10.1063/1.1484550 (3 pages) | Cited 4 times

Online Publication Date: 10 June 2002

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Brillouin light scattering from silicon oxynitride films grown on GaAs reveals an excitation at frequencies lying below that of the Rayleigh surface wave. The mode, identified as a localized interfacial excitation, arises from the presence of a soft, thin transition layer between the film and substrate. The results are discussed in the framework of a Green’s function formalism that reproduces the experimental features and illustrates the nature of the mode and its difference from Stoneley excitations that exist in special cases for an abrupt interface separating two semi-infinite solid media. Observations of this low-frequency excitation offer a previously unexplored approach to characterize, nondestructively, the elastic properties of buried interfaces. © 2002 American Institute of Physics.
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78.35.+c Brillouin and Rayleigh scattering; other light scattering
78.66.Li Other semiconductors

Preliminary investigations of infrared Er-related photoluminescence in ion-implanted In0.07Ga0.93N

M. R. Correia, S. Pereira, A. Cavaco, E. Pereira, and E. Alves

Appl. Phys. Lett. 80, 4504 (2002); http://dx.doi.org/10.1063/1.1484545 (3 pages) | Cited 3 times

Online Publication Date: 10 June 2002

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We report the observation of the 1.54 μm emission from optically excited Er3+ in an ion-implanted In0.07Ga0.93N layer epitaxially strained grown by metalorganic chemical vapor deposition. The Er was implanted at 150 keV with a dose of 1×1015 Er+ cm−2 at room temperature. After annealing the sample at 400 °C during 30 min in a vacuum, the intraionic 4I13/2→4I15/2 transition was observed. Photoluminescence studies were carried out in the temperature range from 70–250 K under below band gap excitation. The dominant line emission at 1.5353 μm revealed complex temperature dependence. Two activation energies of 33±4 meV and 189±86 meV were calculated. © 2002 American Institute of Physics.
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78.55.Cr III-V semiconductors
61.72.uj III-V and II-VI semiconductors

Ratio of deuterium to hydrogen termination on silicon surface in aqueous electrolyte solutions

Olga P. Chikalova-Luzina and Takahiro Matsumoto

Appl. Phys. Lett. 80, 4507 (2002); http://dx.doi.org/10.1063/1.1485314 (3 pages)

Online Publication Date: 10 June 2002

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The ratio of deuterium (D)- to hydrogen (H)-adatom concentrations on Si crystal surfaces in hydrogenated and deuterated electrolyte solutions was evaluated by the theory of the elementary act of proton transfer reactions. The result shows that the ratio is determined by the difference between configurational chemical potentials of the isotope reactants. In the temperature range of 273–373 K, the ratio is about 1 at steady-state conditions and somewhat lower at electrochemical equilibrium conditions, and decreases slowly as the temperature increases. © 2002 American Institute of Physics.
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68.43.Fg Adsorbate structure (binding sites, geometry)
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces

Green luminescence of Er3+ in stoichiometric KYb(WO4)2 single crystals

X. Mateos, F. Güell, M. C. Pujol, M. A. Bursukova, R. Solé, Jna. Gavaldà, M. Aguiló, F. Díaz, and J. Massons

Appl. Phys. Lett. 80, 4510 (2002); http://dx.doi.org/10.1063/1.1486477 (3 pages) | Cited 9 times

Online Publication Date: 10 June 2002

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We grew good-optical-quality KYb(WO4)2 single crystals doped with erbium ions by the top seeded solution growth slow cooling method. Optical absorption of erbium was performed at room temperature (RT) and at 6 K. Green photoluminescence of erbium was achieved at RT and 6 K after selective excitation of ytterbium ions at 940 nm (10 638 cm−1). The splitting of all found excited energy levels and the ground energy level of erbium in KYb(WO4)2 is presented derived from the accurate absorption and emission measurements, respectively. The lifetime of the Stokes and the anti-Stokes green emissions of erbium were measured after excitation at 488 nm (20 490 cm−1) and 940 nm(10 638 cm−1), respectively. We propose applying the up-conversion model to the observed green emission. © 2002 American Institute of Physics.
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78.55.Hx Other solid inorganic materials
78.30.Hv Other nonmetallic inorganics

Three-dimensional phase field microelasticity theory of a complex elastically inhomogeneous solid

Yu U. Wang, Yongmei M. Jin, and Armen G. Khachaturyan

Appl. Phys. Lett. 80, 4513 (2002); http://dx.doi.org/10.1063/1.1486249 (3 pages) | Cited 9 times

Online Publication Date: 10 June 2002

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A phase field microelasticity theory of a three-dimensional anisotropic solid with arbitrary elastic and structural inhomogeneities is proposed. The theory is based on the strain energy for the elastically and structurally inhomogeneous system as a functional of the phase field, which is the effective misfit strain of the “equivalent” homogeneous modulus system. It is demonstrated that the misfit strain minimizing this functional fully determines the exact elastic equilibrium in the elastically and structurally inhomogeneous solid. The misfit strain minimizer is obtained as a steady-state solution of the time-dependent Ginzburg–Landau equation. Examples of the elastic equilibrium of an elastically inhomogeneous solid under applied stress are considered. © 2002 American Institute of Physics.
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46.25.Cc Theoretical studies
62.20.D- Elasticity

Reaction steps of silicidation in ZrO2/SiO2/Si layered structure

Kouichi Muraoka

Appl. Phys. Lett. 80, 4516 (2002); http://dx.doi.org/10.1063/1.1486046 (3 pages) | Cited 30 times

Online Publication Date: 10 June 2002

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Reaction steps of silicidation in ZrO2/SiO2/Si layered structure have been investigated in terms of ultrahigh vacuum annealing. Comparison of 2- and 20-nm ZrO2 films at 920 °C revealed that the trigger of silicidation is the contact of ZrO2, SiO, and Si accompanying disappearance of interfacial SiO2 layer due to SiO desorption. In the contact position, a small amount of SiO gas can easily change ZrO2 to ZrSi2. Moreover, this reaction model is also applicable to the silicidation of gate polycrystalline-Si (poly-Si)/ZrO2 interface. © 2002 American Institute of Physics.
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68.35.Fx Diffusion; interface formation
81.05.Cy Elemental semiconductors
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
61.72.Cc Kinetics of defect formation and annealing
66.30.Ny Chemical interdiffusion; diffusion barriers
68.43.Mn Adsorption kinetics

Optical metastability in undoped GaN grown on Ga-rich GaN buffer layers

Subhabrata Dhar and Subhasis Ghosh

Appl. Phys. Lett. 80, 4519 (2002); http://dx.doi.org/10.1063/1.1482145 (3 pages) | Cited 18 times

Online Publication Date: 10 June 2002

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Investigations on defect-related optical metastability in undoped GaN epilayers grown on GaN buffer layers are presented. The III/V ratio in the buffer layer was varied over a range such that the resistivity of the GaN epilayers traversed a semiconducting to semi-insulating transition. The high-resistive and semi-insulating GaN epilayers show photo induced metastability, which is revealed through a number of features: (i) the intensity of the blue luminescence band decreases as the intensity of the yellow luminescence band increases; (ii) quenching of photocurrent; and (iii) persistent photoconductivity, under the illumination of a low-power ultraviolet laser. It has been shown that these unwanted transient effects can be eliminated in the GaN epilayers by reducing the III/V ratio in the buffer layer. A qualitative discussion of these results suggests that the metastable defects, which are associated with both yellow and blue luminescence bands, may have important consequences for our understanding of defect-related luminescence in GaN. © 2002 American Institute of Physics.
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73.61.Ey III-V semiconductors
78.55.Cr III-V semiconductors
81.05.Ea III-V semiconductors
78.66.Fd III-V semiconductors
73.50.Pz Photoconduction and photovoltaic effects
72.60.+g Mixed conductivity and conductivity transitions
72.40.+w Photoconduction and photovoltaic effects
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
61.72.-y Defects and impurities in crystals; microstructure
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Shock wave response of a zirconium-based bulk metallic glass and its composite

Shiming Zhuang, Jun Lu, and Guruswami Ravichandran

Appl. Phys. Lett. 80, 4522 (2002); http://dx.doi.org/10.1063/1.1485300 (3 pages) | Cited 28 times

Online Publication Date: 10 June 2002

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A zirconium-based bulk metallic glass, Zr41.2Ti13.8Cu12.5Ni10Be22.5 (Vit 1), and its composite, Zr56.3Ti13.8Cu6.9Ni5.6Nb5.0Be12.5 (β-Vit), were subjected to planar impact loading. A surprisingly low amplitude elastic precursor and bulk wave, corresponding to the elastic response of the “frozen structure” of the intact metallic glasses, were observed to precede the rate-dependent large deformation shock wave. A concave downward curvature after the initial increase of the Us–Up shock Hugoniots suggests that a phase-change-like transition occurred during shock compression. Further, compression damage occurred due to the shear localization. The spalling in Vit 1 was induced by shear localization, while in β-Vit, it was due to debonding of the β-phase boundary from the matrix. The spall strengths at strain rate of 2×106 s−1 were determined to be 2.35 and 2.11 GPa for Vit 1 and β-Vit, respectively. © 2002 American Institute of Physics.
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62.50.-p High-pressure effects in solids and liquids
61.43.Fs Glasses
81.40.Lm Deformation, plasticity, and creep
62.20.F- Deformation and plasticity
81.30.Bx Phase diagrams of metals, alloys, and oxides

Structural behavior of Zr52Ti5Cu18Ni15Al10 bulk metallic glass at high temperatures

Norbert Mattern, Jürgen Eckert, Uta Kühn, Helmut Hermann, Jan Sakowski, Gerhard Herms, and Jörg Neuefeind

Appl. Phys. Lett. 80, 4525 (2002); http://dx.doi.org/10.1063/1.1486480 (3 pages) | Cited 9 times

Online Publication Date: 10 June 2002

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The structural behavior of the Zr52Ti5Cu18Ni15Al10 bulk glass-forming alloy has been investigated in situ by means of high-temperature x-ray synchrotron diffraction. The dependence of the structure factor of the glass can be well described with a Debye–Waller factor and a Debye temperature θ = 412 K. At the glass transition, the structure factor significantly decreases due to additional thermal excitations. The extrapolation of the structure factor of the supercooled liquid to temperatures above the liquidus curve is in agreement with experimentally determined values of the melt. The short-range order of the glass, of the supercooled liquid state, and of the equilibrium melt at T = 1193 K, is found to be quite similar. The formation of complex chemically ordered clusters in the melt is proposed to be essential for the high-glass-forming ability of this alloy. © 2002 American Institute of Physics.
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61.43.Fs Glasses
63.70.+h Statistical mechanics of lattice vibrations and displacive phase transitions
61.25.Mv Liquid metals and alloys
63.50.-x Vibrational states in disordered systems
64.70.P- Glass transitions of specific systems
64.70.Q- Theory and modeling of the glass transition
64.70.D- Solid-liquid transitions

Temperature dependence of the growth front roughening of oligomer films

D. Tsamouras and G. Palasantzas

Appl. Phys. Lett. 80, 4528 (2002); http://dx.doi.org/10.1063/1.1484250 (3 pages) | Cited 8 times

Online Publication Date: 10 June 2002

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Growth front roughening characteristics of vacuum deposited pentamer 2,5-di-n-octyloxy-1,4-bis[4-(styryl)styryl]-benzene oligomer thin films, onto silicon substrates, strongly depend on the substrate temperature in the range ∼20 °C–100 °C. The measured roughness exponents H increase from H ≈ 0.4 at low substrate temperatures where growth is dominated by vacancy formation, to H ≈ 0.7–0.8 at elevated temperatures where diffusive growth takes place. Moreover, the root-mean-square roughness amplitude and the correlation length evolve with temperature closely as an Arrhenius process with activation barrier comparable to molecule transnational and rotational barriers on oligomer surfaces. © 2002 American Institute of Physics.
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68.55.A- Nucleation and growth
68.35.B- Structure of clean surfaces (and surface reconstruction)
81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
81.15.Aa Theory and models of film growth
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
61.72.J- Point defects and defect clusters
68.35.Fx Diffusion; interface formation
68.43.Jk Diffusion of adsorbates, kinetics of coarsening and aggregation

Reversible changes in the lattice site structure for In implanted into GaN

K. Lorenz, F. Ruske, and R. Vianden

Appl. Phys. Lett. 80, 4531 (2002); http://dx.doi.org/10.1063/1.1485117 (3 pages) | Cited 12 times

Online Publication Date: 10 June 2002

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The perturbed angular correlation method was employed to study the lattice environment of In implanted into GaN. It was found, after annealing the implantation induced damage, that 65% of the implanted atoms were situated in regular undisturbed Ga lattice sites. The remaining fraction showed an unusual behavior insofar as its lattice surroundings changed reversibly from undisturbed at temperatures above 600 K to strongly disturbed at low temperatures. © 2002 American Institute of Physics.
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61.72.uj III-V and II-VI semiconductors
81.05.Ea III-V semiconductors
85.40.Ry Impurity doping, diffusion and ion implantation technology
76.80.+y Mössbauer effect; other γ-ray spectroscopy
61.66.Fn Inorganic compounds
61.72.Cc Kinetics of defect formation and annealing

Specific volume of glass-forming liquid Pd43Cu27Ni10P20 and related thermodynamic aspects of the glass transition

I.-R. Lu, G. P. Görler, and R. Willnecker

Appl. Phys. Lett. 80, 4534 (2002); http://dx.doi.org/10.1063/1.1487922 (3 pages) | Cited 12 times

Online Publication Date: 10 June 2002

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The volume change of the easy glass-forming alloy Pd43Cu27Ni10P20 was investigated continuously from the liquid to the vitreous state upon cooling at 10 K/min by means of the sessile drop technique. From the data obtained on density and thermal expansion, the specific volume as a function of temperature was deduced in the complete temperature range of the stable and the undercooled liquid as well as in the vitreous state for this alloy. Thus, the temperature dependence of the specific volume V(T) could be compared over the entire liquid range of a metallic glass former to that of the enthalpy H(T) obtained from preceding calorimetric measurements. A strong correlation between both thermodynamic functions becomes evident from this comparison and is interpreted on the basis of free-volume theory. The increase of the heat capacity at the glass transition can be explicitly explained by the creation and annihilation of free volume. © 2002 American Institute of Physics.
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64.70.P- Glass transitions of specific systems
64.70.Q- Theory and modeling of the glass transition
65.60.+a Thermal properties of amorphous solids and glasses: heat capacity, thermal expansion, etc.
81.05.Kf Glasses (including metallic glasses)
61.43.Fs Glasses

Contact-induced defect propagation in ZnO

J. E. Bradby, S. O. Kucheyev, J. S. Williams, C. Jagadish, M. V. Swain, P. Munroe, and M. R. Phillips

Appl. Phys. Lett. 80, 4537 (2002); http://dx.doi.org/10.1063/1.1486264 (3 pages) | Cited 32 times

Online Publication Date: 10 June 2002

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Contact-induced damage has been studied in single-crystal (wurtzite) ZnO by cross-sectional transmission electron microscopy (XTEM) and scanning cathodoluminescence (CL) monochromatic imaging. XTEM reveals that the prime deformation mechanism in ZnO is the nucleation of slip on both the basal and pyramidal planes. Some indication of dislocation pinning was observed on the basal slip planes. No evidence of either a phase transformation or cracking was observed by XTEM in samples loaded up to 50 mN with an ∼4.2 μm radius spherical indenter. CL imaging reveals a quenching of near-gap emission by deformation-produced defects. Both XTEM and CL show that this comparatively soft material exhibits extensive deformation damage and that defects can propagate well beyond the deformed volume under contact. Results of this study have significant implications for the extent of contact-induced damage during fabrication of ZnO-based (opto)electronic devices. © 2002 American Institute of Physics.
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62.20.F- Deformation and plasticity
81.05.Dz II-VI semiconductors
68.35.Gy Mechanical properties; surface strains
62.20.M- Structural failure of materials
62.20.Qp Friction, tribology, and hardness
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
68.37.Lp Transmission electron microscopy (TEM)
78.60.Hk Cathodoluminescence, ionoluminescence
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Effect of Ga content on defect states in CuIn1−xGaxSe2 photovoltaic devices

J. T. Heath, J. D. Cohen, W. N. Shafarman, D. X. Liao, and A. A. Rockett

Appl. Phys. Lett. 80, 4540 (2002); http://dx.doi.org/10.1063/1.1485301 (3 pages) | Cited 28 times

Online Publication Date: 10 June 2002

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Defects in the band gap of CuIn1−xGaxSe2 have been characterized using transient photocapacitance spectroscopy. The measured spectra clearly show response from a band of defects centered around 0.8 eV from the valence band edge as well as an exponential distribution of band tail states. Despite Ga contents ranging from Ga/(In+Ga) = 0.0 to 0.8, the defect bandwidth and its position relative to the valence band remain constant. This defect band may act as an important recombination center, contributing to the decrease in device efficiency with increasing Ga content. © 2002 American Institute of Physics.
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71.55.Ht Other nonmetals
81.05.Hd Other semiconductors
84.60.Jt Photoelectric conversion
71.20.Nr Semiconductor compounds
72.40.+w Photoconduction and photovoltaic effects
61.66.Bi Elemental solids
61.66.Dk Alloys

Theoretical valence band offsets of semiconductor heterojunctions

Kyurhee Shim and Herschel Rabitz

Appl. Phys. Lett. 80, 4543 (2002); http://dx.doi.org/10.1063/1.1483904 (3 pages) | Cited 2 times

Online Publication Date: 10 June 2002

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A theoretical model is presented to predict the valence band offsets of heterojunction semiconductors. The total valence band offsets are split into bulk and interfacial contributions. The bulk contributions are based on the tight binding approach while the localized effects at the interface are described by the bond exchange and the elastic energy due to the strained layer. We calculate the valence band offsets for various types of heterojunctions and compare that with experimental data and the results of other theoretical calculations. Our results are in good agreement with experimental data for most of the systems explored. This suggests that the present model is generic and contains the dominant physical factors operative at the interface to make it applicable to various heterojunctions. © 2002 American Institute of Physics.
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73.20.At Surface states, band structure, electron density of states
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
71.15.Ap Basis sets (LCAO, plane-wave, APW, etc.) and related methodology (scattering methods, ASA, linearized methods, etc.)
71.45.Gm Exchange, correlation, dielectric and magnetic response functions, plasmons

Anti-domain-free GaP, grown in atomically flat (001) Si sub-μm-sized openings

B. J. Ohlsson, J.-O. Malm, A. Gustafsson, and L. Samuelson

Appl. Phys. Lett. 80, 4546 (2002); http://dx.doi.org/10.1063/1.1485311 (3 pages) | Cited 3 times

Online Publication Date: 10 June 2002

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We demonstrate a method for growth of GaP nanocrystals on Si(001), developed to avoid defects related to antiphase domain boundaries in the proximity of the GaP/Si interface. The technique is based on sub-μm-sized selective-area epitaxy of GaP on atomically flat Si in masked openings. We have used field-emission scanning electron microscopy together with transmission electron microscopy to illustrate the method with examples of monocrystalline GaP nanocrystals. The optical properties of the nanocrystals were investigated by low-temperature cathodoluminescence. © 2002 American Institute of Physics.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
78.60.Hk Cathodoluminescence, ionoluminescence
81.07.Bc Nanocrystalline materials
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
61.46.-w Structure of nanoscale materials

Electroreflectance of the AlGaN/GaN heterostructure and two-dimensional electron gas

S. R. Kurtz, A. A. Allerman, D. D. Koleske, and G. M. Peake

Appl. Phys. Lett. 80, 4549 (2002); http://dx.doi.org/10.1063/1.1487447 (3 pages) | Cited 13 times

Online Publication Date: 10 June 2002

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A contacted electroreflectance technique was used to characterize the electronic properties of AlGaN/GaN heterostructures and field-effect transistors. By studying variations in the electroreflectance with applied electric field, spectral features associated with the AlGaN barrier, the two-dimensional electron gas at the interface, and bulk GaN were observed. The AlGaN barrier displayed Franz–Keldysh oscillations which provided estimates of barrier-layer composition and electric field. The electron gas Fermi energy was determined from analysis of the broad two-dimensional electron gas feature. © 2002 American Institute of Physics.
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78.66.Fd III-V semiconductors
78.20.Jq Electro-optical effects
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.61.Ey III-V semiconductors
73.20.At Surface states, band structure, electron density of states

Decrease in the leakage current density of Si-based metal–oxide–semiconductor diodes by cyanide treatment

Akira Asano, Asuha, Osamu Maida, Yoshihiro Todokoro, and Hikaru Kobayashi

Appl. Phys. Lett. 80, 4552 (2002); http://dx.doi.org/10.1063/1.1484249 (3 pages) | Cited 23 times

Online Publication Date: 10 June 2002

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Crown-ether cyanide treatment, which includes the immersion of Si in KCN solutions containing 18-crown-6 molecules, is found to greatly decrease the leakage current density of Si-based metal–oxide–semiconductor (MOS) diodes. The decrease by one order of magnitude for the single crystalline Si-based MOS diodes is attributable to the elimination of Si/SiO2 interface states by reaction with cyanide ions and formation of Si–CN bonds. The reduction in the leakage current density by two orders of magnitude is caused for polycrystalline Si-based MOS diodes, and this decrease is attributed to the passivation of trap states in poly-Si as well as the interface states. © 2002 American Institute of Physics.
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85.30.Tv Field effect devices
85.30.Kk Junction diodes
73.20.At Surface states, band structure, electron density of states
73.61.Cw Elemental semiconductors
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)

Characteristics of MgO/GaN gate-controlled metal–oxide– semiconductor diodes

Jihyun Kim, R. Mehandru, B. Luo, F. Ren, B. P. Gila, A. H. Onstine, C. R. Abernathy, S. J. Pearton, and Y. Irokawa

Appl. Phys. Lett. 80, 4555 (2002); http://dx.doi.org/10.1063/1.1487903 (3 pages) | Cited 56 times

Online Publication Date: 10 June 2002

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Gate-controlled n+p metal–oxide–semiconductor diodes were fabricated in p-GaN using MgO as a gate dielectric and Si+ implantation to create the n+ regions. This structure overcomes the low minority carrier generation rate in GaN and allowed observation of clear inversion behavior in the dark at room temperature. By contrast, diodes without the n+ regions to act as an external source of minority carriers did not show inversion even at measurement temperatures of 300 °C. The gated diodes showed the expected shape of the current–voltage characteristics, with clear regions corresponding to depletion and inversion under the gate. The MgO was deposited prior to the Si implantation and was stable during the activation annealing for the Si-implanted n+ regions. © 2002 American Institute of Physics.
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85.30.Kk Junction diodes
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
61.72.uj III-V and II-VI semiconductors
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
85.40.Ry Impurity doping, diffusion and ion implantation technology
61.72.Cc Kinetics of defect formation and annealing
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