Mutual Passivation in Dilute GaNxAs1-x Alloys

2005 ◽  
Vol 864 ◽  
Author(s):  
K. M. Yu ◽  
W. Walukiewicz ◽  
J. Wu ◽  
D. E. Mars ◽  
M. A. Scarpulla ◽  
...  
Keyword(s):  
Nearest Neighbor ◽  
Diffusion Length ◽  
Average Distance ◽  
Alloy System ◽  
Group Iv ◽  
Semiconductor Alloys ◽  
Drastic Reduction ◽  
Free Electron Concentration ◽  
Ternary Semiconductor ◽  
Good Agreement

AbstractThe dilute GaNxAs1-x alloys (with x up to 0.05) have exhibited many unusual properties as compared to the conventional binary and ternary semiconductor alloys. We report on a new effect in the GaNxAs1-x alloy system in which electrically active substitutional group IV donors and isoelectronic N atoms passivate each other's activity. This mutual passivation occurs in dilute GaNxAs1-x doped with group IV donors through the formation of nearest neighbor IVGa- NAs pairs when the samples are annealed under conditions such that the diffusion length of the donors is greater than or equal to the average distance between donor and N atoms. The passivation of the shallow donors and the NAs atoms is manifested in a drastic reduction in the free electron concentration and, simultaneously, an increase in the fundamental bandgap. This mutual passivation effect is demonstrated in both Si and Ge doped GaNxAs1-x alloys. Analytical calculations of the passivation process based on Ga vacancy mediated diffusion show good agreement with the experimental results.

Temporal Changes in Habitat Selection and Nest Spacing in a Colony of Ross' and Lesser Snow Geese

The Auk ◽  
1983 ◽  
Vol 100 (2) ◽  
pp. 335-343 ◽  
Author(s):  
M. Robert McLandress
Keyword(s):  
Nearest Neighbor ◽  
Average Distance ◽  
Habitat Preferences ◽  
Nearest Neighbors ◽  
Nest Density ◽  
Snow Goose ◽  
Snow Geese ◽  
Lesser Snow Geese ◽  
Average Size ◽  
Island Habitats

Abstract I studied the nesting colony of Ross' Geese (Chen rossii) and Lesser Snow Geese (C. caerulescens caerulescens) at Karrak Lake in the central Arctic of Canada in the summer of 1976. Related studies indicated that this colony had grown from 18,000 birds in 1966-1968 to 54,500 birds in 1976. In 1976, geese nested on islands that were used in the late 1960's and on an island and mainland sites that were previously unoccupied. Average nest density in 1976 was three-fold greater than in the late 1960's. Consequently, the average distance to nearest neighbors of Ross' Geese in 1976 was half the average distance determined 10 yr earlier. The mean clutch size of Ross' Geese was greater in island habitats where nest densities were high than in less populated island or mainland habitats. The average size of Snow Goose clutches did not differ significantly among island habitats but was larger at island than at mainland sites. Large clutches were most likely attributable to older and/or earlier nesting females. Habitat preferences apparently differed between species. Small clutches presumably indicated that young geese nested in areas where nest densities were low. The establishment of mainland nesting at Karrak Lake probably began with young Snow Geese using peripheral areas of the colony. Young Ross' Geese nested in sparsely populated habitats on islands to a greater extent than did Snow Geese. Ross' Geese also nested on the mainland but in lower densities than Ross' Geese nesting in similar island habitats. Successful nests with the larger clutches had closer conspecific neighbors than did successful nests with smaller clutches. The species composition of nearest neighbors changed significantly with distance from Snow Goose nests but not Ross' Goose nests. Nesting success was not affected by the species of nearest neighbor, however. Because they have complementary antipredator adaptations, Ross' and Snow geese may benefit by nesting together.

LATTICE DYNAMICS OF THE BINARY APERIODIC CHAINS OF ATOMS I: FRACTAL DIMENSION OF PHONON SPECTRA

1995 ◽  
Vol 09 (12) ◽  
pp. 1429-1451 ◽  
Author(s):  
WŁODZIMIERZ SALEJDA
Keyword(s):  
Fractal Dimension ◽  
Lattice Dynamics ◽  
Nearest Neighbor ◽  
Average Distance ◽  
Local Maximum ◽  
Fractal Dimensions ◽  
Dimension Formula ◽  
Phonon Spectra ◽  
Wide Range ◽  
Silver Mean

The microscopic harmonic model of lattice dynamics of the binary chains of atoms is formulated and studied numerically. The dependence of spring constants of the nearest-neighbor (NN) interactions on the average distance between atoms are taken into account. The covering fractal dimensions [Formula: see text] of the Cantor-set-like phonon spec-tra (PS) of generalized Fibonacci and non-Fibonaccian aperiodic chains containing of 16384≤N≤33461 atoms are determined numerically. The dependence of [Formula: see text] on the strength Q of NN interactions and on R=mH/mL, where mH and mL denotes the mass of heavy and light atoms, respectively, are calculated for a wide range of Q and R. In particular we found: (1) The fractal dimension [Formula: see text] of the PS for the so-called goldenmean, silver-mean, bronze-mean, dodecagonal and Severin chain shows a local maximum at increasing magnitude of Q and R>1; (2) At sufficiently large Q we observe power-like diminishing of [Formula: see text] i.e. [Formula: see text], where α=−0.14±0.02 and α=−0.10±0.02 for the above specified chains and so-called octagonal, copper-mean, nickel-mean, Thue-Morse, Rudin-Shapiro chain, respectively.

A Dynamic Model of III-V Ternary Semiconductor Alloys in the Epitaxial Growth

1994 ◽  
Vol 340 ◽  
Author(s):  
Bing-Lin Gu ◽  
Jing-Zhi Yu ◽  
Xiao Hu ◽  
Kaoru Ohno ◽  
Yoshiyuki Kawazoe
Keyword(s):  
Dynamic Model ◽  
Ground State ◽  
Wave Method ◽  
Semiconductor Alloys ◽  
Concentration Wave ◽  
Surface Layers ◽  
Ordered Structures ◽  
Effective Interactions ◽  
Ternary Semiconductor ◽  
The Difference

ABSTRACTA concentration wave method for several interpenetrating Bravais sublattices is presented by considering the intralayer and interlayer effective interactions and the difference between the surface layers and the deeper layers in III – V alloys. The ground state ordered structures of ternary III – V semiconductor alloys are deduced and a dynamic model is established.

Theory of Defects, Doping, Surfaces and Interfaces in Wide Gap Nitrides

1996 ◽  
Vol 423 ◽  
Author(s):  
J. Bernholc ◽  
P. Boguslawski ◽  
E. L. Briggs ◽  
M. Buongiorno Nardelli ◽  
B. Chen ◽  
...  
Keyword(s):  
Nearest Neighbor ◽  
Group Iv ◽  
Type I ◽  
Shallow Acceptor ◽  
Surface And Interface ◽  
Al Content ◽  
Surfaces And Interfaces ◽  
High Concentrations ◽  
P Type ◽  
High Al Content

AbstractThe results of extensive theoretical studies of group IV impurities and surface and interface properties of nitrides are presented and compared with available experimental data. Among the impurities, we have considered substitutional C, Si, and Ge. CN is a very shallow acceptor, and thus a promising p-type dopant. Both Si and Ge are excellent donors in GaN. However, in AlGaN alloys the DX configurations are stable for a sufficiently high Al content, which quenches the doping efficiency. At high concentrations, it is energetically favorable for group IV impurities to form nearest-neighbor Xcation-XN pairs. Turning to surfaces, AIN is known to exhibit NEA. We find that the NEA property depends sensitively on surface reconstruction and termination. At interfaces, the strain effects on the band offsets range from 20% to 40%, depending on the substrate. The AIN/GaN/InN interfaces are all of type I, while the A10.5Ga0.5 N/A1N zinc-blende (001) interface may be of type II. Further, the calculated bulk polarizations in wurtzite AIN and GaN are -1.2 and -0.45 μC/cm2, respectively, and the interface contribution to the polarization in the GaN/AlN wurtzite multi-quantum-well is small.

Structural and Electrical Properties of Tin and Carbon Co-Implanted Silicon

1990 ◽  
Vol 201 ◽  
Author(s):  
P. Mei ◽  
M. T. Schmidt ◽  
P. W. Li ◽  
E. S. Yang ◽  
B. J. Wilkens
Keyword(s):  
Electrical Properties ◽  
Secondary Ion Mass Spectrometry ◽  
Alloy System ◽  
Group Iv ◽  
Carbon Ions ◽  
Depth Profiles ◽  
Structural And Electrical Properties ◽  
Group Iv Semiconductor ◽  
Work Samples ◽  
Secondary Ion

AbstractThe alloy system Six(SnyC1-y)1-x was investigated. In this work, samples were prepared by co-implantation of tin and carbon ions into silicon wafers with dosage range 1015 − 1016cm−2, followed by rapid thermal annealing. Rutherford backscattering channeling, Auger sputter profiling, and secondary ion mass spectrometry were employed to study the crystallinity, chemical composition and depth profiles. A near perfect crystallinity for 0.5% at. of tin and carbon was achieved. To study the electrical properties in the implanted materials, diode I-V measurements were performed. The data show near ideal p-n junctions in the co-implanted region. This work demonstrates promising features of group IV semiconductor synthesis by ion implantation.

Photonic Band Structure of Nanochannel Glass Materials

1996 ◽  
Vol 431 ◽  
Author(s):  
A. Rosenberg ◽  
R. J. Tonucci ◽  
H.-B. Lin
Keyword(s):  
Band Structure ◽  
Brillouin Zone ◽  
Near Infrared ◽  
Nearest Neighbor ◽  
Dielectric Structure ◽  
Zone Boundary ◽  
Photonic Band Structure ◽  
Brillouin Zone Boundary ◽  
Photonic Band ◽  
Good Agreement

AbstractWe demonstrate that nanochannel glass (NCG) materials are ideal for investigating twodimensional (2D) photonic band-structure effects. The NCG materials we have studied consist of triangular arrays of glass cylinders embedded in a glass matrix, having center-tocenter nearest-neighbor separations from 0.54 to 1.08 μm. The indices of refraction of the two glasses differ by less than 0.02 in the relevant spectral region. Narrow attenuation features occur whenever the dispersion relation for light propagating within such a periodic dielectric structure crosses a Brillouin zone boundary. The attenuations corresponding to the first Brillouin zone appear in the near-infrared (IR), at wavelengths between 1 and 3 μm, in good agreement with calculations.

Atomic Interchange Potentials Calculation of Ni-Al-Cr Alloy Based on Microscopic Phase Field Method

2013 ◽  
Vol 747-748 ◽  
pp. 739-746
Author(s):  
Wei Ping Dong ◽  
Zhang Jing ◽  
Zheng Chen
Keyword(s):  
Field Theory ◽  
Phase Field ◽  
Nearest Neighbor ◽  
Field Method ◽  
Phase Field Method ◽  
Precipitation Process ◽  
Atomic Interaction ◽  
Long Range Order ◽  
Nearest Neighbour ◽  
Good Agreement

The effects of increasing atomic interchange potentials to the precipitation process and microstructure of Ni-Al-Cr alloy have been simulated based on the microscopic phase field theory. The first nearest neighbour atomic interchange potentials of Ni-Al-Cr alloys for L12 and D022 phase was calculated out according to the formula which were referenced on the relation equation between atomic interchange potentials and long range order parameters by Khachaturyan. The results indicated that Ni-Al (WNi-Al) and Ni-Cr (WNi-Cr) s first nearest neighbor atomic interaction potentials will increase linearly while the temperatures rose. Moreover WNi-Al increased but WNi-Cr decreased roughly linearly if Al atoms concentration rose, and conversely inversed. In addition, these atomic interchange potentials changing with temperature and concentration were in good agreement with earlier study.

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