摘要:

Transmission electron microscopy analysis of tin dioxide films grown by aerosol‐assisted chemical vapor deposition onto oxidized or etched silicon displayed the formation of a sub‐oxide phase that was identified as Sn2O3. Such a phase is observed to disappear upon heat treatment, and is believed to be one of the factors responsible for the instability of tin dioxide films used as gas sensing layers. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115970

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

c‐axis oriented Bi4Ti3O12films have been prepared on Pt/Ti/Si(111) substrates by sol‐gel process. Crack‐free films of 0.5 &mgr;m thickness were fabricated using a multilayer spinning technique and calcination at 600 °C for 30 min. The average grain size of the film is about 0.15 &mgr;m. The film exhibits ferroelectric hysteresis with remanent polarizationPr=4.8 &mgr;c/cm2and coercive fieldEc=70 kV/cm. The measured dielectric constant and loss factor at a frequency of 100 kHz are 170 and 0.02 respectively. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115971

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Crystalline CNx/TiN multilayer composite coatings have been synthesized using an opposed cathode unbalanced magnetron sputtering system. Electron microscopy studies showed that the CNx/TiN coatings were fully crystalline and dense at small bilayer thicknesses. An amorphous phase was formed when the CNxlayer thickness exceeded 4–5 nm. Two newdspacings extracted by Fourier transform of digitized images of the crystalline CNxregion cannot be matched by known compounds formed by the detected elements. This provides limited evidence for the possible formation of a new carbon–nitrogen compound. Nanoindentation hardness about 45–55 GPa was reproducibly achieved for coatings produced under low nitrogen partial pressure and high substrate bias (−150 to −250 V). TiN (111) preferred orientation was strongly correlated to the high coating hardness. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115972

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The role of ion energy over the range 5 eV≤E≤20 keV in the production of the dense diamondlikesp3‐bonded phase of carbon films deposited from ion beams has been investigated. Films with a significantsp3component (≳40%), as determined by electron energy loss spectroscopy (EELS), can be formed over the wide energy region 30 eV≤E≤10 keV at room temperature. Thesp3fraction is completely suppressed only forE≤10 eV orE≥20 keV. For both cases, this suppression is associated with a sharp increase of the surface roughness, as determined by atomic force microscopy (AFM). The different nature of the mechanisms responsible for the suppression ofsp3bonding in both the low and high energy regions is discussed. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115973

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We have studied the influence of chemical ordering on the properties of GaInP/AlGaInP optical waveguide structures and lasers. We have observed mode‐conversion between transverse electric (TE) and transverse magnetic (TM) modes within typically 60 &mgr;m. We show that an ordering‐induced birefringence with the optical axis tilted with respect to the growth direction is responsible for the coupling of the TE and TM modes. A new linear combination of TE and TM modes, the ‘‘super modes,’’ can propagate in the waveguide without change. We show that these super modes govern the polarization of lasers made from ordered material. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115974

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

High‐quality homoepitaxial diamond films having large terrace width have been successfully grown on (001) diamond substrates. Schottky contact properties as well as the surface morphology and the film crystallinity of the deposited films were characterized in order to examine a potential for electronic applications. It is found that the diamond films are covered with macroscopic steps running parallel to [110] direction and have atomically flat surfaces with 2×1 and 1×2 double‐domain structure. Detailed analysis of the atomic force microscope image for the atomically flat region indicates that the terrace width for double atomic steps is around 50 nm, suggesting that the migration length of precursors under present condition is much longer than that previously reported. The current–voltage characteristics of Al–Schottky contacts to these diamond films show excellent rectification properties. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115932

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We investigate the dynamics of photoexcited carriers in silicon after interband excitation with optical femtosecond pulses by probing intraband transitions with time‐delayed THz pulses. The experimental data at various temperatures are compared with numerical, self‐consistent solutions of the intraband polarization and Maxwell’s equations. In addition, we deduce the carrier scattering rate from the comparison between experiment and theory. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115933

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We have investigated the effect of hydrostatic pressure on interdiffusion in multilayers composed of alternating layers of amorphous Si (2.7 nm) and Ge (3.1 nm). Samples were annealed at 420 °C at pressures between 0 and 2.8 GPa in an externally heated diamond anvil cell. Interdiffusion was measured by monitoring the decay with annealing time of the intensity of the first‐order x‐ray reflection resulting from the effects of composition modulation. The decay curves for all pressures could be made to coincide by scaling the annealing times. This made it possible to separate the effects of pressure on the interdiffusivity from those of composition and structural relaxation. The interdiffusivity increased with applied pressure, with an activation volume of −5.0 cm3/mole, or −0.42 times the atomic volume of crystalline Si. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115934

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The outdiffusion of boron, antimony, and phosphorus from the bare silicon wafer at 1200 °C, especially its dependence upon the annealing atmosphere, has been studied with spreading resistance and secondary ion mass spectroscopy (SIMS). It is found that the boron outdiffusion proceeds when the crystal is annealed in hydrogen, but is completely suppressed in argon even if the doping concentration is as high as 3×1018cm−3and the annealing time is as long as 2 h. The dramatic dependence upon the atmosphere has not been observed for the other impurities and is temporarily related with the desorption process of boron atoms from the surface. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115935

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Outstanding surface passivation of low‐resistivity single‐crystallinep‐silicon is reported using silicon nitride fabricated at low temperature (375 °C) in a remote plasma‐enhanced chemical vapor deposition system. The effective surface recombination velocitySeffis determined as a function of the bulk injection level from light‐biased photoconductance decay measurements. On polished as well as chemically textured silicon wafers we find that our remote plasma silicon nitride provides better surface passivation than the best high‐temperature thermal oxides ever reported. For polished 1.5 and 0.7 &OHgr; cmp‐silicon wafers, record lowSeffvalues of 4 and 20 cm/s, respectively, are presented. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115936

出版商:AIP    

年代:1996

数据来源: AIP