摘要:

We have studied nucleation and growth of diamond on nickel substrate by microwave plasma assisted chemical vapor deposition followed byin situcarbon–hydrogen solution treatment. The Raman depth profiles of isolated diamond crystals on the (100) and (111) surfaces were measured by confocal Raman spectroscopy. In the case of the crystals having the [111] growth direction, the1332 cm−1diamond peak was observed near the diamond–nickel interface and it shifted1323 cm−1towards the surface. The1323 cm−1peak may be assigned to “hexagonal diamond.” The in-depth spectral change from cubic to hexagonal was observed in chemical vapor deposited diamond crystals. The chemical and/or structural effects of nickel substrate for dissolved carbon are essential for specific diamond crystallization. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121994

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

SinceSr0.6Ba0.4Nb2O6(SBN) is ferroelectric with a tungsten–bronze structure, numerous needlelike ferroelectric domains appear in a SBN single crystal when it is cooled through its transition temperature in the absence of a poling field. If the domains were illuminated by 1.06 &mgr;m radiation from a Nd:YAG laser, second-harmonic diffuse light was generated from these domains. This interesting effect, which can clearly be seen with the naked eye, will be used to generate all the primary colors using suitable lasers. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121995

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We have investigated the swelling of organic–inorganic structures based on fluorocarbon polymer(CF2)layers sandwiched by two layers of inorganic ionic(HfO2)and inorganic covalent (CdS) materials. The swelling of theCF2layer produces cracks on the uppermost inorganic layer. The cracks form a network of hexagonal defects with random distribution. The extension of the pattern and the mean unit size have been measured for different solvents by using a purposely developed optical profilometer. We show that the swelling phenomenon strongly depends on the polar forces between the molecules of the solvent and those of the inorganic layers. The electric dipole moment of the solvents and the ionicity of the inorganic materials are thus the crucial parameters influencing the crack density and shape. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121996

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The effect of the silicon top layer on the uptake and release of deuterium by silicon implanted with oxygen (SIMOX) was studied using thermal desorption measurements. The deuterium is incorporated in the buried oxide by disruption of the Si–O bridging bonds. The data reveal that the top layer reduces the uptake at 1073 K. Furthermore, it retards release; a moderate (≈1125 K) and a high-temperature (≈1400 K) retention were observed. It is proposed that release is accompanied by the reconstruction of the Si–O bonds and that the bare oxide surface constitutes an abundant source for defects thus enhancing the generation and elimination of Si–O bridging bond defects. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121997

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Exploiting the high brilliance of synchrotron radiation, we performed surface-sensitive and depth-resolved x-ray scattering experiments on thin films of boron nitride grown on Si(001) substrates. In-plane strains of different structural phases, namely turbostratic and cubic, grain sizes and textures were determined. Annealing the films up to temperatures of1000 °Cleads to large strain relaxation of about 70&percent;, while the grain size stays constant at 80 Å. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121998

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

A field effect transistor fabricated with an oxide channel has been shown to demonstrate switching characteristics similar to conventional silicon metal oxide field effect transistors. This device is believed to operate via a Mott metal-insulator transition induced by the gate field, and offers a potential technology alternative for the regime beyond silicon scaling limitations. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121999

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Low excess noise in avalanche photodetectors (APDs) is desired for improved sensitivity and high-frequency performance. Gain and noise characteristics are measured for InAlAsp-i-nhomojunction APDs that were grown with varyingi-region widths on InP by molecular beam epitaxy. The effective ionization ratiok (&bgr;/&agr;)determined by noise measurements shows a dependence on multiplication region width, reducing from 0.31 to 0.18 for multiplication region thicknesses of 1600–200 nm. This trend follows previously shown results in AlGaAs-based APDs, which exhibit reduced excess noise due to nonlocal multiplication effects. These results show that this effect is a characteristic of thin avalanche regions and is not a material-specific phenomenon. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.122000

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Ordering of Cu and In atoms in near-stoichiometricCuInS2epitaxial films grown on Si (111) by molecular beam epitaxy was studied by transmission electron microscopy. Nonchalcopyrite ordering of the metal atoms inCuInS2is observed, which is identified as CuAu-type ordering. Sharp spots in electron diffraction patterns reveal the ordered Cu and In atom planes alternating along the [001] direction over a long range. High-resolution electron microscopy confirms this ordering. The CuAu-ordered structure coexists with the chalcopyrite ordered structure, in agreement with theoretical prediction. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.122001

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

PolycrystallineSrBi2Ta2O9(SBT) ferroelectric thin films were synthesized onPt/Ti/SiO2/Sisubstrates by metalorganic decomposition. Electric measurements demonstrate that fatigue increases with decreasing switching voltage and frequency, and the suppressed polarization caused at a lower switching voltage can be recovered by switching at a higher voltage. This suggests that the domain walls of SBT thin films are weakly pinned and easily depinned by a higher external field. The polarization of SBT thin films annealed in air shows more degradation than that annealed in oxygen, which indicates that the oxygen vacancy also plays an important role in fatigue behavior of SBT thin films. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.122002

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We demonstrate the use of low-energy cathodoluminescence spectroscopy (CLS) to study optical transitions at defect bonding arrangements atSi–SiO2interfaces prepared by low-temperature plasma deposition. Variable-depth excitation achieved by different electron injection energies provides a clear distinction between luminescence derived from (i) the near-interface region of the oxide film, (ii) theSi–SiO2interface, and (iii) the underlying crystalline Si substrate. Cathodoluminescence bands at ∼0.8 and 1 eV are assigned to interfacial Si atom dangling bonds with different numbers of back-bonded Si and O atoms. CLS also reveals higher photon energy features: two bands at ∼1.9 and 2.7 eV assigned to suboxide bonding defects in the as-grown oxide films, as well as a substrate-related feature at ∼3.4 eV. The effects of hydrogenation at 400 °C and rapid thermal annealing at 900 °C, and especially the combination of both process steps is shown to dramatically reduce the intensities of the CLS features assigned to interfacial and suboxide bonding defects. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.122003

出版商:AIP    

年代:1998

数据来源: AIP