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

20 Oct 2008

Volume 93, Issue 16, Articles (16xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 93, 161101 (2008); http://dx.doi.org/10.1063/1.3000630 (3 pages)

E. Mujagić, L. K. Hoffmann, S. Schartner, M. Nobile, W. Schrenk, M. P. Semtsiv, M. Wienold, W. T. Masselink, and G. Strasser
Enlarge Image | Read More
Page 1 of 4 Pages Next Page | Jump to Page
back to top
RSS Feeds

Low divergence single-mode surface emitting quantum cascade ring lasers

E. Mujagić, L. K. Hoffmann, S. Schartner, M. Nobile, W. Schrenk, M. P. Semtsiv, M. Wienold, W. T. Masselink, and G. Strasser

Appl. Phys. Lett. 93, 161101 (2008); http://dx.doi.org/10.1063/1.3000630 (3 pages) | Cited 17 times

Online Publication Date: 20 October 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We describe the fabrication and operation of surface emitting second-order distributed feedback quantum cascade ring lasers. The devices exhibit single-mode emission at a wavelength of 3.95 μm with a side mode suppression ratio of 25 dB. A linear tuning coefficient of 0.13 cm−1/K is observed. A single longitudinal mode in the ring shaped resonator results in a highly symmetric far-field pattern and a low beam divergence, represented by a full width at half maximum of ∼ 3°. Based on these characteristics the presented compact coherent light source may find its way into today’s midinfrared spectroscopy applications.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.60.Fc Modulation, tuning, and mode locking
42.86.+b Optical workshop techniques

Superconducting single photon detectors with minimized polarization dependence

S. N. Dorenbos, E. M. Reiger, N. Akopian, U. Perinetti, V. Zwiller, T. Zijlstra, and T. M. Klapwijk

Appl. Phys. Lett. 93, 161102 (2008); http://dx.doi.org/10.1063/1.3003579 (3 pages) | Cited 12 times

Online Publication Date: 20 October 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Superconducting single photon detectors are usually fabricated in such a way that a polarization dependence of the quantum efficiency is inevitable. Their meandering nanowire leads to a preferential polarization absorption, this is undesired in experiments where the polarization degree of freedom is used. We have designed two new geometries for which the polarization dependence is minimized: a detector with two meander-type parts oriented perpendicular with respect to each other and a spiraling detector. Focusing on individual parts of the detectors shows polarization dependent quantum efficiency. When the detectors are illuminated uniformly, the maximum polarization dependent quantum efficiency cannot be achieved, however, the polarization dependence of the quantum efficiency is minimized.
Show PACS
85.25.Oj Superconducting optical, X-ray, and γ-ray detectors (SIS, NIS, transition edge)
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors

Simple theoretical model for the temperature stability of InAs/GaAs self-assembled quantum dot lasers with different p-type modulation doping levels

C. Y. Jin, H. Y. Liu, Q. Jiang, M. Hopkinson, and O. Wada

Appl. Phys. Lett. 93, 161103 (2008); http://dx.doi.org/10.1063/1.3003874 (3 pages) | Cited 4 times

Online Publication Date: 20 October 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have developed a simple theoretical model to account for the effects of different p-doping levels on the temperature-dependent performance of InAs/GaAs self-assembled quantum dot (QD) lasers. An assumption of equal occupation probabilities among QDs has been applied for operating conditions near the lasing threshold. Theoretical results indicate that there is an optimum p-doping region, which can provide the lowest temperature dependence of lasing threshold at room temperature.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems

Study of the characteristics of 1.55 μm quantum dash/dot semiconductor lasers on InP substrate

D. Zhou, R. Piron, F. Grillot, O. Dehaese, E. Homeyer, M. Dontabactouny, T. Batte, K. Tavernier, J. Even, and S. Loualiche

Appl. Phys. Lett. 93, 161104 (2008); http://dx.doi.org/10.1063/1.3005194 (3 pages) | Cited 7 times

Online Publication Date: 20 October 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
InAs quantum dash (QDH) and quantum dot (QD) lasers grown by molecular beam epitaxy on InP substrate are studied. The laser active zones with multiple stacked layers exhibit lasing wavelength at 1.55 μm. On these devices, the experimental threshold current density reaches its minimum value for a double stacked QDH/QD structure. Other basic laser properties such as gain and quantum efficiency are compared. QD lasers exhibit better threshold current densities but equivalent modal gain per layer than QDH. Finally, the analysis of the modal gain on QD lasers shows a promising potential for improvement.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems

Aberration-free imaging for light and electrons

B. Fluegel and A. Mascarenhas

Appl. Phys. Lett. 93, 161105 (2008); http://dx.doi.org/10.1063/1.3005582 (3 pages) | Cited 1 time

Online Publication Date: 20 October 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The equations for refraction of either the extraordinary wave of light or the wavefunction of an electron at a planar boundary between two misoriented uniaxially anisotropic materials are shown via raytracing to yield a transverse displacement of the object point. The displacement is independent of ray incidence angle and is thus free from spherical aberration, yielding a perfect virtual image which can have applications in birefringent optics. The general conditions for this aberration-free imaging are found to be identical to those required for amphoteric total refraction.
Show PACS
42.25.Gy Edge and boundary effects; reflection and refraction
42.25.Lc Birefringence
42.30.-d Imaging and optical processing
42.15.Dp Wave fronts and ray tracing
41.75.Fr Electron and positron beams

Fabrication and characterization of ultrafast carbon nanotube saturable absorbers for solid-state laser mode locking near 1 μm

Jong Hyuk Yim, Won Bae Cho, Soonil Lee, Yeong Hwan Ahn, Kihong Kim, Hanjo Lim, Günter Steinmeyer, Valentin Petrov, Uwe Griebner, and Fabian Rotermund

Appl. Phys. Lett. 93, 161106 (2008); http://dx.doi.org/10.1063/1.2999593 (3 pages) | Cited 35 times

Online Publication Date: 21 October 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Transmitting and reflecting ultrafast saturable absorbers based on single-walled carbon nanotubes are developed that are applicable for stable mode locking of bulk solid-state lasers operating near 1 μm. For fabrication of these saturable absorbers, relatively simple spin coating and spray methods are employed. Parameters important for stable mode locking, such as transient nonlinear absorption, saturation fluence, and recovery time, are investigated by nonlinear transmission and time-resolved pump-probe measurements near 1 μm. Typical modulation depths and recovery times amount to ∼ 0.21%–0.25% and <1 ps, respectively.
Show PACS
42.60.Fc Modulation, tuning, and mode locking
81.07.De Nanotubes
42.50.Gy Effects of atomic coherence on propagation, absorption, and amplification of light; electromagnetically induced transparency and absorption

Millisecond Brillouin scattering spectroscopy

Yasuo Minami, Takeshi Yogi, and Keiji Sakai

Appl. Phys. Lett. 93, 161107 (2008); http://dx.doi.org/10.1063/1.3002301 (3 pages) | Cited 4 times

Online Publication Date: 21 October 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The millisecond Brillouin spectroscopy was developed and applied for the real-time observation of phonons in solid and gas materials. The Brillouin spectra of solid (polymethylmethacrylate) and gas (air) at 300 K are observed over the wave number range from k = 8.1×104 m−1 to k = 5.3×105 m−1. The measurement time is only 100 ms, which is by far shorter than that for the conventional method from several minutes to several hours. The technique would provide us with a useful tool for the dynamic observation of thermal phonons in solid and gas.
Show PACS
78.35.+c Brillouin and Rayleigh scattering; other light scattering
42.65.Es Stimulated Brillouin and Rayleigh scattering
51.70.+f Optical and dielectric properties

Native-oxide-confined high-index-contrast λ = 1.15 μm strain-compensated InGaAs single quantum well ridge waveguide lasers

D. Liang, D. C. Hall, J. Y.-T. Huang, G. Tsvid, and L. J. Mawst

Appl. Phys. Lett. 93, 161108 (2008); http://dx.doi.org/10.1063/1.3001587 (3 pages) | Cited 1 time

Online Publication Date: 22 October 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
High performance native-oxide-confined high-index-contrast (HIC) ridge waveguide (RWG) diode lasers are fabricated in a strain-compensated In0.4Ga0.6As single quantum well structure by employing a deep dry etch plus nonselective O2-enhanced wet thermal oxidation process. The thermal native oxide grown on the etch-exposed RWG sidewalls of the Al0.74Ga0.26As waveguide cladding layers and GaAs core with GaAsP–InGaAs quantum well provides both strong optical and electrical confinements for the active region. Due to a smoothing of sidewall roughness by the O2-enhanced oxidation, the lasers exhibit a low internal loss in αi = 7.2 cm−1 for a w = 7.2 μm narrow stripe HIC RWG structure, only 53% larger than that of w = 87.2 μm broad-area devices, enabling their room temperature operation at a low 300 A/cm2 threshold current density.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
68.47.Fg Semiconductor surfaces
81.65.Mq Oxidation

Label-free porous silicon membrane waveguide for DNA sensing

Guoguang Rong, Judson D. Ryckman, Raymond L. Mernaugh, and Sharon M. Weiss

Appl. Phys. Lett. 93, 161109 (2008); http://dx.doi.org/10.1063/1.3005620 (3 pages) | Cited 26 times

Online Publication Date: 22 October 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report a label-free porous silicon membrane waveguide biosensor based on a 1 μm thick freestanding porous silicon film with 100 nm diameter pores. The sensor operates in the Kretschmann configuration. A formvar polymer film provides robust adhesion of the porous silicon membrane to a rutile prism and enables confinement of guided modes in the porous silicon membrane. Attenuated total reflectance measurements are performed, along with theoretical calculations, to fully characterize the waveguide. The sensitivity of the sensor is investigated through DNA hybridization in the porous silicon membrane. A detection limit of 42 nM was demonstrated for 24-base pair DNA oligonucleotides.
Show PACS
87.85.-d Biomedical engineering
87.85.J- Biomaterials
87.85.Rs Nanotechnologies-applications

Surface-emitting terahertz quantum cascade laser source based on intracavity difference-frequency generation

Christian Pflügl, Mikhail A. Belkin, Qi Jie Wang, Markus Geiser, Alexey Belyanin, Milan Fischer, Andreas Wittmann, Jérôme Faist, and Federico Capasso

Appl. Phys. Lett. 93, 161110 (2008); http://dx.doi.org/10.1063/1.3009198 (3 pages) | Cited 8 times

Online Publication Date: 24 October 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report a surface-emitting terahertz source based on intracavity difference-frequency generation in dual-wavelength midinfrared quantum cascade lasers with integrated giant second-order nonlinear susceptibility. The terahertz light is coupled out of the waveguide by a second-order grating etched into the laser ridges. In contrast to sources where the difference-frequency radiation is extracted from the facet, this approach enables extraction of the terahertz emission from the whole length of the device even when the coherence length is small.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.65.An Optical susceptibility, hyperpolarizability
42.79.Dj Gratings
back to top
RSS Feeds

The plasma transistor: A microcavity plasma device coupled with a low voltage, controllable electron emitter

K.-F. Chen and J. G. Eden

Appl. Phys. Lett. 93, 161501 (2008); http://dx.doi.org/10.1063/1.2981573 (3 pages) | Cited 7 times

Online Publication Date: 22 October 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A microplasma transistor has been realized by injecting electrons into the sheath of a rare gas plasma with a low voltage (|Vb|<25 V), controllable electron emitter. Integrating a solid state emitter with a 500 μm diam. cylindrical microcavity plasma yields a three terminal current-controlled device capable of modulating the conduction current and light intensity generated by the microplasma. For an emitter voltage of Vb = −10 V, the rms charge carried by the conduction current of a Ne microplasma is tripled relative to the value measured for no current injection. Similarly, the wavelength-integrated visible emission is increased by 2.7 and 4 dB for Vb = −5 and −25 V, respectively. From the continuity equation for charged particle flux in the sheath, the electron density at the edge of the sheath is determined to be ns = (3±1)×1012 cm−3 for an electron temperature in the 1–5 eV range. Energizing the electron emitter is estimated to reduce the ratio of the ion to electron number densities at the cathode surface from 25 to 14. A parameter βp, defined as the microplasma transistor conductance normalized to that for the conventional plasma device (i.e., Vb = 0), is introduced and found to be ∼ 40 for this unoptimized device when |Vb| = 5 V.
Show PACS
52.75.-d Plasma devices
52.40.Kh Plasma sheaths
52.25.-b Plasma properties
42.82.Et Waveguides, couplers, and arrays
42.79.Gn Optical waveguides and couplers

Observation of near total polarization in the ultrafast laser ablation of Si

Yaoming Liu, Sima Singha, Tana E. Witt, Yongtao Cheng, and Robert J. Gordon

Appl. Phys. Lett. 93, 161502 (2008); http://dx.doi.org/10.1063/1.3000966 (3 pages) | Cited 7 times

Online Publication Date: 22 October 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report nearly completely polarized emission from the plasma produced in the femtosecond ablation of Si(111). Pairs of ultrashort laser pulses were focused onto the target in air, and the polarization spectrum was measured as a function of energy, pulse delay, and polarization state of the laser. When the laser was focused on the surface, the fluorescence continuum was strongly polarized, whereas discrete lines appeared as minima in the polarization spectrum. Under this focusing condition, the continuum polarization increased with pulse delay and decreased with pulse energy and fluorescence wavelength, with >95% polarization in the ultraviolet.
Show PACS
79.20.Ds Laser-beam impact phenomena
42.25.Ja Polarization
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
52.38.Mf Laser ablation
back to top
RSS Feeds

Optical properties of MoO3 containing tellurite glasses

Rajan Jose, Yusuke Arai, and Yasutake Ohishi

Appl. Phys. Lett. 93, 161901 (2008); http://dx.doi.org/10.1063/1.2976133 (3 pages) | Cited 1 time

Online Publication Date: 20 October 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
It was observed that P2O5 generates TeO5+δ groups in tellurite glasses that have a profound influence on their optical properties. The presence of TeO5+δ groups in phosphotellurite glass made MoO3 behave in a different way compared to other tellurite glass systems that do not contain P2O5. The refractive index measurements and Raman spectroscopy were combined to show that the addition of MoO3 in a phosphotellurite glass generates TeO3+1 polyhedron, whereas it generates TeO3 trigonal bipyramids in other glass systems. The MoO3 system showed absorption bands corresponding to Mo5+ ion in phosphotellurite glasses, whereas no similar bands were observed for other glasses.
Show PACS
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
78.35.+c Brillouin and Rayleigh scattering; other light scattering

Time scale for point-defect equilibration in nanostructures

Paul C. Millett, Dieter Wolf, Tapan Desai, and Vesselin Yamakov

Appl. Phys. Lett. 93, 161902 (2008); http://dx.doi.org/10.1063/1.3005175 (3 pages) | Cited 3 times

Online Publication Date: 20 October 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Molecular dynamics simulations of high-temperature annealing are performed on nanostructured materials enabling direct observation of vacancy emission from planar defects (i.e., grain boundaries and free surfaces) to populate the initially vacancy-free grain interiors on a subnanosecond time scale. We demonstrate a universal time-length scale correlation that governs these re-equilibration processes, suggesting that nanostructures are particularly stable against perturbations in their point-defect concentrations, caused for example by particle irradiation or temperature fluctuations.
Show PACS
61.43.Bn Structural modeling: serial-addition models, computer simulation
61.72.jd Vacancies
61.72.Mm Grain and twin boundaries
61.72.Cc Kinetics of defect formation and annealing
61.80.Az Theory and models of radiation effects
61.82.Rx Nanocrystalline materials

Tunable transmission and harmonic generation in nonlinear metamaterials

Ilya V. Shadrivov, Alexander B. Kozyrev, Daniel W. van der Weide, and Yuri S. Kivshar

Appl. Phys. Lett. 93, 161903 (2008); http://dx.doi.org/10.1063/1.2999634 (3 pages) | Cited 28 times

Online Publication Date: 21 October 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We study the properties of a tunable nonlinear metamaterial operating at microwave frequencies. We fabricate the nonlinear metamaterial composed of double split-ring resonators and wires where a varactor diode is introduced into each resonator so that the magnetic resonance can be tuned dynamically by varying the input power. We show that at higher powers the transmission of the metamaterial becomes power dependent, and we demonstrate experimentally power-dependent transmission properties and selective generation of higher harmonics.
Show PACS
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.79.-e Optical elements, devices, and systems
42.70.-a Optical materials

Study of nanoprecipitates in a nickel-based superalloy using small-angle neutron scattering and transmission electron microscopy

E-Wen Huang, Peter K. Liaw, Lionel Porcar, Yun Liu, Yee-Lang Liu, Ji-Jung Kai, and Wei-Ren Chen

Appl. Phys. Lett. 93, 161904 (2008); http://dx.doi.org/10.1063/1.3002288 (3 pages) | Cited 7 times

Online Publication Date: 21 October 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Small-angle neutron scattering (SANS) experiments were performed on a Ni-based nanoprecipitate-strengthened superalloy. A theoretical model for SANS absolute intensity distribution I(Q) was presented to extract the structural properties. During the deformation process, a change in the morphology of precipitates was discovered. However, the average interprecipitate distance and the average volume of precipitates were found to remain invariant. This microstructural information resolved by SANS is in good agreement with the results obtained from the quantitative transmission-electron-microscopy image analysis.
Show PACS
64.70.Nd Structural transitions in nanoscale materials
61.05.fg Neutron scattering (including small-angle scattering)

Violet-light spontaneous and stimulated emission from ultrathin In-rich InGaN/GaN multiple quantum wells grown by metalorganic chemical vapor deposition

Ho-Sang Kwack, Bong-Joon Kwon, Jin-Soo Chung, Yong-Hoon Cho, Soon-Yong Kwon, Hee Jin Kim, and Euijoon Yoon

Appl. Phys. Lett. 93, 161905 (2008); http://dx.doi.org/10.1063/1.3002300 (3 pages) | Cited 1 time

Online Publication Date: 21 October 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We investigated the spontaneous and stimulated emission properties of violet-light-emitting ultrathin In-rich InGaN/GaN multiple quantum wells (MQWs) with indium content of 60%–70%. The Stokes shift was smaller than that of In-poor InGaN MQWs, and the emission peak position at 3.196 eV was kept constant with increasing pumping power, indicating negligible quantum confined Stark effect in ultrathin In-rich InGaN MQWs despite of high indium content. Optically pumped stimulated emission performed at room temperature was observed at 3.21 eV, the high-energy side of spontaneous emission, when the pumping power density exceeds ∼ 31 kW/cm2.
Show PACS
78.67.De Quantum wells
78.45.+h Stimulated emission

Electron diffraction with ten nanometer beam size for strain analysis of nanodevices

A. Armigliato, S. Frabboni, and G. C. Gazzadi

Appl. Phys. Lett. 93, 161906 (2008); http://dx.doi.org/10.1063/1.3003581 (3 pages) | Cited 5 times

Online Publication Date: 21 October 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A method to perform nanobeam diffraction (NBD) in a transmission electron microscope with high spatial resolution and low convergence angle is proposed. It is based on the use of a properly fabricated condenser aperture of 1 μm in diameter, which allows an electron beam about 10 nm in size to be focused on the sample, with a convergence angle in the 0.1 mrad range. Examples of NBD patterns taken in an untilted ⟨110⟩ cross section of a silicon device are shown. Their quality is adequate for spot position determination and hence to obtain, in principle, quantitative strain information.
Show PACS
85.35.-p Nanoelectronic devices
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices

Efficient oxygen gettering in Si by coimplantation of hydrogen and helium

Xin Ou, Reinhard Kögler, Arndt Mücklich, Wolfgang Skorupa, Wolfhard Möller, Xi Wang, Jürgen W. Gerlach, and Bernd Rauschenbach

Appl. Phys. Lett. 93, 161907 (2008); http://dx.doi.org/10.1063/1.3005595 (3 pages) | Cited 3 times

Online Publication Date: 21 October 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Hydrogen preimplantation performed in addition to helium implantation efficiently shrinks the width of the gettering layer in Si and increases the empty volume fraction as well as the internal surface area per unit volume. The gettering efficiency for oxygen is significantly enhanced compared to the single helium implantation, and the helium implantation dose can be strongly reduced. The gas-filled bubble layer induced by the coimplantation of hydrogen and helium has the highest gettering efficiency for the oxygen accumulation. Direct evidence for oxygen gettering at the internal wall of the cavity is demonstrated by cross-sectional transmission electron microscopy.
Show PACS
61.72.uf Ge and Si
81.65.Tx Gettering
68.47.Fg Semiconductor surfaces
61.80.Jh Ion radiation effects
68.37.Og High-resolution transmission electron microscopy (HRTEM)

Anisotropic in-plane strains in nonpolar AlN and AlGaN (11math0) films grown on SiC (11math0) substrates

Tetsuya Akasaka, Yasuyuki Kobayashi, and Makoto Kasu

Appl. Phys. Lett. 93, 161908 (2008); http://dx.doi.org/10.1063/1.2995994 (3 pages) | Cited 2 times

Online Publication Date: 22 October 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Nonpolar Al1−xGaxN (0 ≤ x ≤ 0.196) (11math0) films were grown on 4H-SiC (11math0) substrates by metal organic vapor phase epitaxy. Al1−xGaxN (0 ≤ x ≤ 0.057) films grew almost pseudomorphically on the substrates due to balanced in-plane stresses along [0001] and [1math00], while Al1−xGaxN (0.057<x) films were strained along [0001] but partially relaxed along [1math00] due to the absence of the balance. The crystal tilts of the films toward [0001] decreased monotonically with increasing Ga composition due to the correspondence between the (0001) plane distances of the films and the (0002) plane distance of substrates and due to a decrease in the in-plane strain along [0001].
Show PACS
81.05.Ea III-V semiconductors
71.55.Eq III-V semiconductors
68.55.ag Semiconductors
68.60.Bs Mechanical and acoustical properties
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.15.Kk Vapor phase epitaxy; growth from vapor phase

Ge dangling bonds at the (100)Ge/GeO2 interface and the viscoelastic properties of GeO2

M. Houssa, G. Pourtois, M. Caymax, M. Meuris, M. M. Heyns, V. V. Afanas’ev, and A. Stesmans

Appl. Phys. Lett. 93, 161909 (2008); http://dx.doi.org/10.1063/1.3006320 (3 pages) | Cited 46 times

Online Publication Date: 23 October 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The electronic energy band structure of a (100)Ge/GeO2 interface with a Ge3 ≡ Ge• center (Ge dangling bond) is calculated using the density functional theory. The defect level associated with this dangling bond is found to lie near the middle of the Ge band gap. Consequently, the Ge dangling bond at this interface should be paramagnetic when the Fermi level is near the midgap, and it should thus be observed by electron spin resonance (ESR), which appears to be in contradiction with the results reported by [ Afanas’ev et al., Appl. Phys. Lett. 87, 032107 (2005) ]. We point out that the density of Ge3 ≡ Ge• centers at the (100)Ge/GeO2 interface is possibly at/below the ESR detection limit due to the viscoelastic properties of GeO2, owing to a better stress relaxation at/near the interface, compared to its silicon counterpart.
Show PACS
68.35.Gy Mechanical properties; surface strains
71.15.Mb Density functional theory, local density approximation, gradient and other corrections
76.30.Mi Color centers and other defects
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.40.+i Anelasticity, internal friction, stress relaxation, and mechanical resonances

Splitting of valance subbands in the wurtzite c-plane InGaN/GaN quantum well structure

Yu Song, Dong Chen, Lai Wang, Hongtao Li, Guangyi Xi, and Yang Jiang

Appl. Phys. Lett. 93, 161910 (2008); http://dx.doi.org/10.1063/1.3007985 (3 pages) | Cited 1 time

Online Publication Date: 24 October 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Peak splitting in the low temperature photoluminescence (PL) spectra of c-plane InGaN/GaN single quantum well samples was observed. For the k∥c configuration, the splitting peaks show a variation in relative intensity as the excitation power is tuned. For the k⊥c configuration, a strong polarization dependence of the luminescence distribution and intensity was spotted. The PL spectra was analyzed with a calculation model based on the k⋅p effective mass theory, and the splitting peaks were identified as free-exciton transitions between the conduction subband C1 and two groups of valence subbands, the {HH1,LH1} and the {HH2,LH2,CH1}, respectively.
Show PACS
73.20.-r Electron states at surfaces and interfaces
71.20.Nr Semiconductor compounds
71.18.+y Fermi surface: calculations and measurements; effective mass, g factor
71.15.-m Methods of electronic structure calculations
78.55.Cr III-V semiconductors

Two-dimensional photonic crystals with anisotropic unit cells imprinted from poly(dimethylsiloxane) membranes under elastic deformation

Xuelian Zhu, Ying Zhang, Dinesh Chandra, Shih-Chieh Cheng, James M. Kikkawa, and Shu Yang

Appl. Phys. Lett. 93, 161911 (2008); http://dx.doi.org/10.1063/1.3006061 (3 pages) | Cited 11 times

Online Publication Date: 24 October 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We study structural symmetries of two-dimensional (2D) photonic crystals with anisotropic unit cells, including square- and rectangular-lattices with orientationally modulated elliptic motifs, and a compound structure consisting of circles with sixfold rotational symmetry and elliptical lines with twofold symmetry, which are created through elastic deformation of a single elastomeric membrane with circular pores. We then investigate the photonic bandgap (PBG) properties of the corresponding 2D Si posts and their tolerance to the structural deviation. We find that in the compound structure the overall PBGs are dominated by the sublattice with a higher symmetry, while the total symmetry is determined by the one with a lower symmetry.
Show PACS
42.70.Qs Photonic bandgap materials
61.50.Ah Theory of crystal structure, crystal symmetry; calculations and modeling
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.D- Elasticity

Sr induced striped surface reconstructions formed on Si(111)

S. Teys, B. Olshanetsky, R. Zhachuk, S. Pereira, and G. Norga

Appl. Phys. Lett. 93, 161912 (2008); http://dx.doi.org/10.1063/1.3005594 (3 pages) | Cited 3 times

Online Publication Date: 24 October 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Surface structures induced by submonolayer Sr adsorption on Si(111) surface were investigated by scanning tunneling microscopy (STM). Depending on the sample temperature and Sr coverage the following reconstructions on Si(111) surface could be directly resolved: 3×2, n×1 (n = 5,7,9), 2math×math, 4math×4math, and math×2 with increasing Sr coverage. The 3×2 and 2math×math striped structures cover large surface areas and are found to have stripe-to-stripe separations of 1.00 and 1.34 nm, respectively. The surface structures and respective rotational and antiphase domains reported here can explain all the previously suggested reconstructions except 2×1, which was not found. It is also demonstrated that diffraction data may lead to ambiguous results regarding the structure periodicity, when structural antiphase domains with sizes below the coherence length are present, highlighting the importance of complementary real space STM analysis.
Show PACS
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.43.-h Chemisorption/physisorption: adsorbates on surfaces
68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)

Origin of tensile stress in the Si substrate induced by TiN/HfO2 metal gate/high-k dielectric gate stack

J. G. Wang, Jiyoung Kim, Chang Yong Kang, Byoung Hun Lee, Raj Jammy, Rino Choi, and M. J. Kim

Appl. Phys. Lett. 93, 161913 (2008); http://dx.doi.org/10.1063/1.3009572 (3 pages)

Online Publication Date: 24 October 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The tensile stress induced by the metal TiN film in the atomic layer deposited HfO2/TiN stacks has been found from the crystallite coalescence mechanism of the Volmer–Weber-type growth mode at the early stage of the TiN film formation. The higher tensile stress induced by 3 nm TiN film than that by the 20 nm TiN film resulted from the smaller grain size and the [200] orientation of the TiN layer. Electron energy loss spectrum profile shows that there is no significant elemental interdiffusion between HfO2 and TiN, which could contribute to stress relaxation.
Show PACS
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.40.+i Anelasticity, internal friction, stress relaxation, and mechanical resonances
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
79.20.Uv Electron energy loss spectroscopy
66.30.Ny Chemical interdiffusion; diffusion barriers
Page 1 of 4 Pages Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close