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

27 Aug 2007

Volume 91, Issue 9, Articles (09xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 91, 093110 (2007); http://dx.doi.org/10.1063/1.2775801 (3 pages)

M. Schmidbauer, Zh. M. Wang, Yu. I. Mazur, P. M. Lytvyn, G. J. Salamo, D. Grigoriev, P. Schäfer, R. Köhler, and M. Hanke
Enlarge Image | Read More
Return to All Sections
back to top
RSS Feeds

Effects of alloying and localized electronic states on the resonant Raman spectra of Zn1−xMgxO nanocrystals

J. D. Ye, K. W. Teoh, X. W. Sun, G. Q. Lo, D. L. Kwong, H. Zhao, S. L. Gu, R. Zhang, Y. D. Zheng, S. A. Oh, X. H. Zhang, and S. Tripathy

Appl. Phys. Lett. 91, 091901 (2007); http://dx.doi.org/10.1063/1.2775813 (3 pages) | Cited 16 times

Online Publication Date: 27 August 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Using resonant Raman spectroscopy, the authors report on the alloying effect and localization of electronic states in Zn1−xMgxO (x<0.15) nanostructures with average sizes in the range of 20–150 nm. Anomalous intensity enhancement of the second-order longitudinal optical phonon has been observed, which is due to Fröhlich interaction via the localized exciton as the resonant intermediate electronic states. The alloying-induced disorder due to Mg incorporation led to the enhancement of exciton localization as well as the asymmetric broadening of longitudinal optical phonon line shape. The composition in ZnMgO could be determined by the first-order longitudinal optical phonon frequency via a bowinglike quadratic fit. This simple relationship is in perfect match to the modified random-element-isodisplacement model and provides a nondestructive approach to probe the quantitative composition distributions in wurtzite ZnMgO alloy system.
Show PACS
78.30.Fs III-V and II-VI semiconductors
78.66.Hf II-VI semiconductors
61.46.-w Structure of nanoscale materials
63.20.kk Phonon interactions with other quasiparticles
63.22.-m Phonons or vibrational states in low-dimensional structures and nanoscale materials
71.55.Gs II-VI semiconductors

Stability and electronic structures of CuxTe

Juarez L. F. Da Silva, Su-Huai Wei, Jie Zhou, and Xuanzhi Wu

Appl. Phys. Lett. 91, 091902 (2007); http://dx.doi.org/10.1063/1.2775835 (3 pages) | Cited 11 times

Online Publication Date: 27 August 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this work, the authors study the stability and electronic properties of CuxTe as a function of the Cu/Te ratio using first-principles calculations. They find that CuxTe shows bistability with energy minimum at x ≈ 1.25 and x ≈ 1.75. At low x, CuxTe is more stable in the tetragonal-based structures, whereas for x>1.47, it is more stable in the trigonal-based structures. The valence-band maximum of Cu2Te is found to be 0.7 eV higher than that of CdTe, indicating that it can easily be doped p type. The Cu diffusion barriers and hole density decrease with increasing Cu concentration, indicating that for x ∼ 2, ionic conductivity may play a role.
Show PACS
71.20.Nr Semiconductor compounds
71.10.-w Theories and models of many-electron systems
71.15.-m Methods of electronic structure calculations
66.30.H- Self-diffusion and ionic conduction in nonmetals

Fast, precise, tomographic measurements of thin films

Young-Sik Ghim and Seung-Woo Kim

Appl. Phys. Lett. 91, 091903 (2007); http://dx.doi.org/10.1063/1.2776015 (3 pages) | Cited 18 times

Online Publication Date: 27 August 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The authors describe a nondestructive measurement method that enables them to obtain the cross-sectional thickness profile of thin-film layers fast with a single operation of measurement. The method is based on spectrally resolved white-light interferometry, being capable of reconstructing the tomographic height map of thin films with depth resolutions in the nanometer range. In terms of the measuring speed and resolution, the proposed method is well suited for the in-line high-speed inspection of microelectronics devices produced in large quantities particularly in the semiconductors and flat panel displays industries.
Show PACS
06.30.Bp Spatial dimensions (e.g., position, lengths, volume, angles, and displacements)
68.55.-a Thin film structure and morphology
07.60.Ly Interferometers
81.70.Fy Nondestructive testing: optical methods

Investigation into the mechanical contact behavior of single asperities using static atomistic simulations

Yeau-Ren Jeng, Wei-Cheng Kao, and Ping-Chi Tsai

Appl. Phys. Lett. 91, 091904 (2007); http://dx.doi.org/10.1063/1.2776019 (3 pages) | Cited 3 times

Online Publication Date: 27 August 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This study employs an atomic-scale model to investigate mechanical contact behaviors of a single asperity, particularly those which take place beyond the elastic limit threshold. The results obtained from the current model are found to be in good agreement with the predictions yielded by continuum theory as the contact behavior of the asperity transits from fully elastic to elastoplastic contact interface. Furthermore, the result shows that adhesion within the single asperity has the negligible influence during the loading stage; however, the adhesion force leads to the sizable clusters of copper atoms on the rigid plate during the unloading stage.
Show PACS
68.35.Gy Mechanical properties; surface strains
62.20.D- Elasticity

Mechanical properties of AlxGa1−xN films with high Al composition grown on AlN/sapphire templates

F. J. Xu, B. Shen, M. J. Wang, J. Xu, L. Lu, Z. L. Miao, Z. J. Yang, Z. X. Qin, G. Y. Zhang, B. Lin, and S. L. Bai

Appl. Phys. Lett. 91, 091905 (2007); http://dx.doi.org/10.1063/1.2735551 (3 pages)

Online Publication Date: 27 August 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Mechanical properties of AlxGa1−xN thin films with high Al composition (0.33 ⩽ x ⩽ 1) grown on AlN/sapphire templates have been investigated by means of the nanoindentation technique. It is found that Young’s modulus E of the films increases with increasing Al composition. In addition, it is also found that the occurrence of the clear and sudden displacement discontinuity (“pop-in”) in the plastic deformation (PD) process is dependent on Al composition in AlxGa1−xN films. The higher Al composition results in less occurrence of the pop-in in the PD process of the films. With increasing Al composition, it is believed that the increase of the bond strength and the decrease of the lattice mismatch between AlxGa1−xN films and AlN/sapphire templates result in greater resistance to the formation of dislocations, which is responsible for the pop-in behavior in AlxGa1−xN films.
Show PACS
68.60.Bs Mechanical and acoustical properties
81.40.Jj Elasticity and anelasticity, stress-strain relations
81.40.Lm Deformation, plasticity, and creep
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
62.20.D- Elasticity
62.20.F- Deformation and plasticity

Raman tensor elements for tetragonal BaTiO3 and their use for in-plane domain texture assessments

Marco Deluca, Masayuki Higashino, and Giuseppe Pezzotti

Appl. Phys. Lett. 91, 091906 (2007); http://dx.doi.org/10.1063/1.2776357 (3 pages) | Cited 7 times

Online Publication Date: 27 August 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A quantitative assessment of c-axis oriented domains in a textured BaTiO3 (BT) single crystal has been carried out by polarized Raman microprobe spectroscopy. The relative intensity modulation of the Raman phonon modes has been theoretically modeled as a function of crystal rotation and linked to the volume fraction of c-axis oriented domains. Raman tensor elements have also been experimentally determined for the Ag and B1 vibrational modes. As an application, the internal in-plane texture and the volume fraction of c-oriented domains in the BT single crystal have been nondestructively visualized by monitoring the relative intensity of Ag and B1 Raman modes.
Show PACS
78.30.Hv Other nonmetallic inorganics
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.80.Dj Domain structure; hysteresis
63.20.D- Phonon states and bands, normal modes, and phonon dispersion

Transmission increase upon switching of VO2 thin films on microstructured surfaces

I. Karakurt, J. Boneberg, P. Leiderer, R. Lopez, A. Halabica, and R. F. Haglund, Jr.

Appl. Phys. Lett. 91, 091907 (2007); http://dx.doi.org/10.1063/1.2776368 (3 pages) | Cited 5 times

Online Publication Date: 27 August 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The authors compare transmission measurements of near-infrared light through VO2 thin films on smooth substrates and on ordered arrays of silica microspheres. When the samples are heated above the critical temperature for the semiconductor-metallic phase transition, smooth thin films show reduced transmission independent of thickness; however, the VO2 film deposited on the microspheres may show either reduced or enhanced transmission, depending on VO2 film thickness. They show that this at a first glance, unexpected behavior is directly related to the change of scattering efficiency upon the phase transition. This suggests that optical transmission through thin-film microstructures could be tuned by an appropriate combination of microsphere ordering and VO2 film thickness.
Show PACS
78.66.Li Other semiconductors
78.30.Hv Other nonmetallic inorganics

Application of parameter-induced stochastic resonance to target detection in shallow-water reverberation

Bohou Xu, Huiquan Zhang, Lingzao Zeng, Jianlong Li, Xingxing Wu, and Zhong-Ping Jiang

Appl. Phys. Lett. 91, 091908 (2007); http://dx.doi.org/10.1063/1.2776856 (3 pages) | Cited 4 times

Online Publication Date: 27 August 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A method based on parameter-induced stochastic resonance is proposed for target echo detection in the presence of shallow-water reverberation. The signal received by the horizontal sensor array is normalized and delayed to form the input to a bistable system. The system parameters are tuned properly to maximize the detection performance based on parameter-induced stochastic resonance techniques. Considering the limitation on the length of receiving arrays, the space-time unfolding method is suggested to largely improve the detection performance.
Show PACS
43.30.Gv Backscattering, echoes, and reverberation in water due to combinations of boundaries
43.30.Vh Active sonar systems
43.25.Gf Standing waves; resonance
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
02.50.Ey Stochastic processes

Long-lifetime emission in luminescent colloidal silica

Ronald B. Soriano, Essoyodou Kpatcha, Adam M. Jakob, Jon W. Merkert, Clifford M. Carlin, and Thomas A. Schmedake

Appl. Phys. Lett. 91, 091909 (2007); http://dx.doi.org/10.1063/1.2771372 (3 pages) | Cited 5 times

Online Publication Date: 27 August 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Calcination of aminopropylsilica spheres generates colloidal silica with tailorable luminescence properties depending on the calcination conditions. After calcining at 550 °C for 20 h, photoexcited luminescent colloidal silica exhibits a bright blue emission (λmax = 375 nm, 3.3 eV) followed by a long-lifetime green photoluminescence centered around 500 nm (2.5 eV), which lasts for more than 10 s at room temperature. Time resolved temperature studies indicate that the long-lifetime green photoluminescence can be fitted by a multiexponential decay function consisting of a regular exponential term and a stretched exponential term with a temperature independent beta parameter consistent with a hopping mechanism.
Show PACS
78.55.Hx Other solid inorganic materials
78.47.-p Spectroscopy of solid state dynamics
82.70.Dd Colloids
81.40.Gh Other heat and thermomechanical treatments
72.20.Ee Mobility edges; hopping transport

Effect of Ga/In ratio on the optical and electrical properties of GaInZnO thin films grown on SiO2/Si substrates

Donghun Kang, Ihun Song, Changjung Kim, Youngsoo Park, Tae Dong Kang, Ho Suk Lee, Jun-Woo Park, Seoung Ho Baek, Suk-Ho Choi, and Hosun Lee

Appl. Phys. Lett. 91, 091910 (2007); http://dx.doi.org/10.1063/1.2773952 (3 pages) | Cited 14 times

Online Publication Date: 27 August 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Amorphous GaInZnO and polycrystalline ZnO thin films are grown by rf magnetron sputtering. Their optical properties are investigated by spectroscopic ellipsometry. The optical gap of the GaInZnO film increases with the increase of Ga content and by annealing. These are attributed to the large band-gap energy of Ga2O3 and the structural relaxation after annealing, respectively. The changes in optical properties show a strong correlation to the device characteristics of GaInZnO thin film transistors: The turn-on voltage increases as the optical gap increases with increasing Ga/In ratio. This study shows that the GaInZnO thin films are as excellent as transparent oxide semiconductors.
Show PACS
78.66.Hf II-VI semiconductors
73.61.Ga II-VI semiconductors
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Nanomovement of azo polymers induced by metal tip enhanced near-field irradiation

Hidekazu Ishitobi, Mamoru Tanabe, Zouheir Sekkat, and Satoshi Kawata

Appl. Phys. Lett. 91, 091911 (2007); http://dx.doi.org/10.1063/1.2777183 (3 pages) | Cited 11 times

Online Publication Date: 27 August 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Nanomovement of azo polymers induced by metal tip enhanced near-field illumination was studied. A protrusion with 47 nm full width at half maximum was induced with a resolution beyond the diffraction limit. At the top of the protrusion, an anisotropic movement occurs in a direction nearly parallel to the polarization of the incident light, and suggests the existence at the tip end of not only a longitudinal but also a lateral component of the electric field of light. The anisotropic photofluidity and the optical gradient force played important roles in the process of the light induced polymer movement.
Show PACS
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
61.41.+e Polymers, elastomers, and plastics

Tunable current-voltage characteristics in polycrystalline calcium copper titanate

Sung-Yoon Chung, Jin-Hoon Choi, and Jong-Kwan Choi

Appl. Phys. Lett. 91, 091912 (2007); http://dx.doi.org/10.1063/1.2777184 (3 pages) | Cited 6 times

Online Publication Date: 27 August 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The nonlinear current-voltage relationship and the subsequent threshold voltage in polycrystalline CaCu3Ti4O12 are found to be easily controlled by simply doping a small amount of supervalent cations, Nb5+ and Ta5+. The authors show that the dopants have a significant effect on the reduction of the electrostatic potential at the grain boundaries, scarcely changing the conductance of the bulk grains. Through microcontact analysis and impedance spectroscopy, the control of the potential barrier at the boundaries was demonstrated to be a key factor for governing the overall current-voltage characteristics. Plausible compensation mechanisms for the excess charge of the added dopants are also discussed.
Show PACS
72.80.-r Conductivity of specific materials
61.72.up Other materials
61.72.Mm Grain and twin boundaries

Homogeneous strain-relaxation effects in La0.67Ca0.33MnO3 films grown on NdGaO3

S. Seiro, E. Koller, Y. Fasano, and Ø. Fischer

Appl. Phys. Lett. 91, 091913 (2007); http://dx.doi.org/10.1063/1.2775033 (3 pages) | Cited 7 times

Online Publication Date: 28 August 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
X-ray diffraction and transport measurements on a series of La0.67Ca0.33MnO3 films grown on (110)-cut NdGaO3 substrates are presented. Contrary to widespread belief assuming strain-free growth, this work shows the presence of strain in a 42 nm film. On increasing thickness structural relaxation occurs, reaching a bulklike state for 500 nm. No evidence of coexistence of strained and relaxed regions is found. The evolution of lattice parameters toward bulk values is accompanied by an increase of the metal-to-insulator transition temperature and a decrease of the polaron activation energy. Therefore, strain effects cannot always be neglected in La0.67Ca0.33MnO3 films grown on small-mismatch NdGaO3.
Show PACS
68.60.Bs Mechanical and acoustical properties
68.55.-a Thin film structure and morphology
75.70.Ak Magnetic properties of monolayers and thin films
75.47.Lx Magnetic oxides
75.47.Gk Colossal magnetoresistance
71.30.+h Metal-insulator transitions and other electronic transitions

Er2O3 as a high-K dielectric candidate

Maria Losurdo, Maria M Giangregorio, Giovanni Bruno, Dongxing Yang, Eugene A. Irene, Alexandra A. Suvorova, and M. Saunders

Appl. Phys. Lett. 91, 091914 (2007); http://dx.doi.org/10.1063/1.2775084 (3 pages) | Cited 12 times

Online Publication Date: 28 August 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Erbium oxide (Er2O3) films have been deposited by metal organic chemical vapor deposition on Si(001) using tris(isopropylcyclopentadienyl)erbium. The impact of Si surface passivation by the metal organic prior growth initiation was investigated. The correlation between the Er2O3 films structure, the optical response, the static dielectric constant (K), and density of interface traps is discussed. An Er-silicate interfacial layer with a thickness of 1.5 nm, a static dielectric constant of 10–12.4, and a density of interface traps of 4.2×1010 cm2 eV−1 measured for a film with a physical thickness of 8.2 nm (with an equivalent oxide thickness of 2.7 nm) render Er2O3 an interesting candidate as a high-K dielectric.
Show PACS
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
77.55.-g Dielectric thin films
68.55.A- Nucleation and growth
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.65.Rv Passivation
77.22.Ch Permittivity (dielectric function)

In situ observation of nanoparticle ordering at the air-water-substrate boundary in colloidal solutions using x-ray nanobeams

S. V. Roth, T. Autenrieth, G. Grübel, C. Riekel, M. Burghammer, R. Hengstler, L. Schulz, and P. Müller-Buschbaum

Appl. Phys. Lett. 91, 091915 (2007); http://dx.doi.org/10.1063/1.2776850 (3 pages) | Cited 18 times

Online Publication Date: 29 August 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The nanoscale structuring during evaporation of a droplet consisting of an aqueous colloidal solution of 2 nm gold nanoparticles in water on a silicon substrate is followed in real time. The authors investigated the transfer of lateral order and vertical layering as a function of time at the three-phase contact line air-solution substrate combining a nanometer-sized x-ray beam with a grazing incidence geometry. A pronounced retardation of vertical ordering is observed with respect to lateral ordering. While individual layers are deposited during evaporation of the solvent, the growth parallel to the substrate shows a strongly nondiffusive behavior.
Show PACS
61.46.Df Structure of nanocrystals and nanoparticles ("colloidal" quantum dots but not gate-isolated embedded quantum dots)
82.70.Dd Colloids
68.03.Fg Evaporation and condensation of liquids
64.70.F- Liquid-vapor transitions

Growth mode transition to pyramid from layer by layer of heteroepitaxial PbTiO3 islands on a (001) vicinal SrTiO3 substrate fabricated by hydrothermal epitaxy

J. H. Jeon and S. K. Choi

Appl. Phys. Lett. 91, 091916 (2007); http://dx.doi.org/10.1063/1.2777171 (3 pages) | Cited 4 times

Online Publication Date: 29 August 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The authors observed the surface morphology transition from the atomically flat two dimensional layer-by-layer mode to the three dimensional pyramidal mode of heteroepitaxial PbTiO3 (PTO) islands synthesized by hydrothermal epitaxy by scanning electron microscopy and atomic force microscopy. Two types of (001) Nb–SrTiO3 (NSTO) with the same step height, ∼ 0.25 and ∼ 1 μm terrace widths, were used for substrates. They found the critical island thickness at which the growth mode of PTO island was converted and its relation to the terrace width of the substrate. It is suggested that the relaxation of the misfit strain, which originates from out-of-plane lattice mismatch between the PTO island unit cell and the NSTO substrate step or somewhere interior of the film, has an effect on the PTO island growth mode transition.
Show PACS
81.15.Lm Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids)
77.55.-g Dielectric thin films
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
68.55.-a Thin film structure and morphology
68.37.Hk Scanning electron microscopy (SEM) (including EBIC)
68.37.Ps Atomic force microscopy (AFM)

Chirality dependence of the energetic stability of 4 Å carbon nanotubes

J. Chen and H. J. Liu

Appl. Phys. Lett. 91, 091917 (2007); http://dx.doi.org/10.1063/1.2778547 (3 pages) | Cited 1 time

Online Publication Date: 30 August 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
First-principles pseudopotential method is used to study the stability of three kinds of 4 Å single-wall carbon nanotubes, which have been recently fabricated inside zeolite channels. The minimum energy path for unrolling the tube into a flat ribbon is calculated by the nudged elastic band technique. Our calculations suggest that all the three kinds of 4 Å tubes are stable when the zeolite framework is dissolved by acid, and the relative stability depends strongly on their chiralities. It is expected that the majority of the grown sample is (3,3) tube in free space.
Show PACS
61.46.Fg Nanotubes

Variation in lattice parameters of 6H-SiC irradiated to extremely low doses

W. Jiang, P. Nachimuthu, W. J. Weber, and L. Ginzbursky

Appl. Phys. Lett. 91, 091918 (2007); http://dx.doi.org/10.1063/1.2778630 (3 pages) | Cited 9 times

Online Publication Date: 30 August 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Irradiation of 6H-SiC single crystals was performed using 4 MeV H+ ions at 340 and 210 K. The changes in lattice parameters in the basal plane and along the c axes were measured as a function of dose using high-resolution x-ray diffraction. The c-axis lattice parameter increases monotonically with the increasing dose, while a-axis lattice parameter decreases at extremely low doses. An initial volumetric contraction of the unit cell is observed. The decrease in the a parameter may originate from the irradiation-induced vacancies and the possible formation of antisite defects that cause the lattice structure on the basal plane to shrink.
Show PACS
61.82.Fk Semiconductors
61.80.Jh Ion radiation effects
61.66.Fn Inorganic compounds
61.72.J- Point defects and defect clusters

Comparison of the low-frequency predicitons of Biot’s and de Boer’s poroelasticity theories with Gassmann’s equation

Boris Gurevich

Appl. Phys. Lett. 91, 091919 (2007); http://dx.doi.org/10.1063/1.2778763 (3 pages) | Cited 2 times

Online Publication Date: 30 August 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Predictions of Biot’s theory (BT) of poroelasticity [J. Acoust. Soc. Am. 28, 168 (1956) ] and de Boer’s theory of porous media (TPM) [ Theory of Porous Media (Springer, Berlin, 2000) ] for the low-frequency bulk modulus of a fluid-saturated porous medium are compared with the Gassmann equation [ Vierteljahrsschr. Naturforsch. Ges. Zur. 96, 1 (1951) ]. It is shown that BT is consistent with the Gassmann equation, whereas TPM is not. It is further shown that the bulk modulus of a suspension of solid particles in a fluid as predicted by TPM is only correct if the particles are incompressible.
Show PACS
46.25.-y Static elasticity
62.20.D- Elasticity
91.60.Lj Acoustic properties

Crystalline SiGe films grown on Si substrates using laser-assisted plasma-enhanced chemical vapor deposition at low temperature

Ching-Ting Lee, Jun-Hung Cheng, and Hsin-Ying Lee

Appl. Phys. Lett. 91, 091920 (2007); http://dx.doi.org/10.1063/1.2779103 (3 pages) | Cited 1 time

Online Publication Date: 30 August 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Compared with conventional plasma-enhanced chemical vapor deposition, laser-assisted plasma-enhanced chemical vapor deposition (LAPECVD) can be used to deposit crystalline SiGe films on Si substrates at low temperature. In the LAPECVD system, a CO2 laser with a wavelength of 10.6 μm was utilized to assist the pyrolytical decomposition of SiH4 and GeH4 reactant gases. The resultant Si0.78Ge0.22 films were obtained and verified through the use of the Auger electron spectroscopy measurement. As the diffraction pattern of a glancing incident angle X-ray diffraction measurement had indicated, several significant diffraction peaks corresponding to a diamond-cubic structure at (111), (220), and (311) were clearly observed. Crystalline SiGe films were also identified by the electron diffraction pattern of high-resolution transmission electron microscopy images.
Show PACS
81.05.Hd Other semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.15.Fg Pulsed laser ablation deposition
68.55.A- Nucleation and growth
68.55.-a Thin film structure and morphology
52.77.Dq Plasma-based ion implantation and deposition

Structural and optical properties of cubic-InN quantum dots prepared by ion implantation in Si (100) substrate

Yi-Kai Huang, Chuan-Pu Liu, Yen-Lin Lai, Cheng-Yu Wang, Yi-Feng Lai, and Hung-Chin Chung

Appl. Phys. Lett. 91, 091921 (2007); http://dx.doi.org/10.1063/1.2766653 (3 pages) | Cited 2 times

Online Publication Date: 30 August 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The authors have synthesized InN quantum dots by ion implantation into a Si (100) substrate followed by a postannealing process. X-ray photoemission spectroscopy data verified the formation of In–N bonding in both as-implanted and postannealed samples. Diffraction patterns from transmission electron microscopy (TEM) confirm that the dots are of cubic crystal (zinc-blende phase) with no presence of wurtzite InN. The silicon matrix provides a constraint for the formation of the InN cubic metastable phase. However, dislocations were revealed by high resolution TEM at the interfaces between the dots and the silicon. In addition, the authors found that as the annealing temperature or time increases, dot size increases and dot density decreases. Furthermore, they demonstrate that the main emission energy of zinc-blende InN dots is about 0.736 eV.
Show PACS
68.65.Hb Quantum dots (patterned in quantum wells)
78.67.Hc Quantum dots
78.55.Cr III-V semiconductors
61.72.uj III-V and II-VI semiconductors
61.82.Fk Semiconductors
61.80.Jh Ion radiation effects

Vacancy-impurity complexes and diffusion of Ga and Sn in intrinsic and p-doped germanium

I. Riihimäki, A. Virtanen, S. Rinta-Anttila, P. Pusa, J. Räisänen, and The ISOLDE Collaboration

Appl. Phys. Lett. 91, 091922 (2007); http://dx.doi.org/10.1063/1.2778540 (3 pages) | Cited 14 times

Online Publication Date: 30 August 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The charge state of mobile vacancy-impurity complexes in germanium was studied via the effect of p-type (Ga) doping on Ga and Sn diffusions. Tin diffusion retards significantly as a function of doping concentration suggesting diffusion dominated by negatively charged vacancy-Sn complexes. Gallium diffusion is practically unaffected by doping, suggesting diffusion dominated by vacancy-Ga complexes having the same charge state as isolated, negatively charged Ga ions. The evident two orders of magnitude higher diffusivity of group V elements in germanium than of group III and IV elements can be well explicated by means of the present findings.
Show PACS
81.05.Cy Elemental semiconductors
71.55.Cn Elemental semiconductors
66.30.J- Diffusion of impurities
61.72.uf Ge and Si
61.72.S- Impurities in crystals
61.72.Yx Interaction between different crystal defects; gettering effect

Luminescence properties of blue La1−xCexAl(Si6−zAlz)(N10−zOz) (z ∼ 1) oxynitride phosphors and their application in white light-emitting diode

Kohsei Takahashi, Naoto Hirosaki, Rong-Jun Xie, Masamichi Harada, Ken-ichi Yoshimura, and Yoshitaka Tomomura

Appl. Phys. Lett. 91, 091923 (2007); http://dx.doi.org/10.1063/1.2779093 (3 pages) | Cited 28 times

Online Publication Date: 31 August 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This letter reports blue oxynitride phosphors of La1−xCexAl(Si6−zAlz)(N10−zOz) (z ∼ 1) (termed JEM crystal phase) and their application for the white light-emitting diodes (LEDs). The JEM phosphor can be excited by 405 nm light efficiently, and its spectrum can be tuned widely by changing the Ce concentration. The emission spectrum of this phosphor is as wide as 110 nm in full width at half maximum, which is convenient to solid state lighting. The preparation of white LED was attempted by using a 405 nm InGaN chip and oxynitride phosphors in this work. High color rendering index >95 was achieved in white LED with various correlated color temperatures, indicating the suitability of the JEM phosphor in solid-state lightings.
Show PACS
78.55.Hx Other solid inorganic materials
85.60.Jb Light-emitting devices

On the structural and energetic properties of the hydrogen absorber Li2Mg(NH)2

C. Moysés Araújo, Ralph H. Scheicher, Puru Jena, and Rajeev Ahuja

Appl. Phys. Lett. 91, 091924 (2007); http://dx.doi.org/10.1063/1.2775803 (3 pages) | Cited 7 times

Online Publication Date: 31 August 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The authors have performed density functional theory based calculations of several possible conformations for the crystal structure of Li2Mg(NH)2 and they confirm the α phase, resolved from both x-ray and neutron diffraction data, as the ground-state configuration. It is also found that although the N–H bond is stronger in Li2Mg(NH)2 than in Li2NH, hydrogen release from Li2Mg(NH)2/LiH mixture displays more favorable thermodynamics than that from the Li2NH/LiH mixture. The insights gained from this seemingly counterintuitive result should prove helpful in the search for promising hydrogen storage materials.
Show PACS
61.66.Fn Inorganic compounds
61.50.Ah Theory of crystal structure, crystal symmetry; calculations and modeling
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close