摘要:

We have studied the effect of ion milling on the surface crystallinity of the metal oxide substratesLaAlO3,SrTiO3,andNdGaO3which are used for fabrication of high-TcJosephson junctions and circuits. Ion channeling of the milled substrates reveals a damage-induced peak corresponding to a disordered layer of≈60 Åat the surface. Annealing the substrates in oxygen ambient at various temperatures ranging from 600 to 1100 °C resulted in the regrowth of the damaged layer at the surface of the substrates as was indicated by the reduction in size of the surface peak observed in the channeled spectrum, as well as by formation of lattice steps as seen by atomic force microscopy. A significant reduction in the damage peak size and the formation of smooth completed lattice steps are seen only after annealing at temperatures⩾950 °C.©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119103

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Ion beam mixing was investigated in crystalline and amorphous Si using molecular dynamics simulations. The magnitude of mixing was found to be larger in amorphous Si by a factor of about 2. The difference is attributed to local relaxation mechanisms occurring during the cooling down phase of the cascade. Comparison of mixing between Si and Al shows that short range structural order also has a significant influence on mixing. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119104

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Nitrogen implantation into amorphous carbon has been studied at various implantation temperatures by using 100 keVN+at 5&mgr;A and fluences of2×1017ions/cm2. The apparent surface hardness and elastic modulus from nanoindentation are well correlated with an asymmetric diffuse peak at around 1500cm−1and a broad band at∼700cm−1in the Raman spectra. Both the enhanced strengths and Raman characteristics show very weak Arrhenius-type implantation-temperature dependence with activation enthalpies of approximately 20 meV in the temperature range 223−1073 K. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119092

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A parallel technique for fabricating single-electron, solid-state capacitance devices from ordered, two-dimensional closest-packed phases of organically functionalized metal nanocrystals is presented. The nanocrystal phases were prepared as Langmuir monolayers and subsequently transferred onto Al-electrode patterned glass substrates for device construction. Alternating current impedance measurements were carried out to probe the single-electron charging characteristics of the devices under both ambient and 77 K conditions. Evidence of a Coulomb blockade and step structure reminiscent of a Coulomb staircase is presented. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119105

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A thin film structure with Ag nanocrystallites embedded in a polycrystallineC60matrix was grown under high vacuum by codeposition of Ag andC60onto the hot substrate. The structural and physical properties of the film were characterized by a transmission electron microscope and a Raman scattering spectrometer. The Ag nanoparticles were well dispersed and not aggregated. An ordered nanoscaleC60lattice was observed between the two adjacent Ag particles, and the Raman-activeAg(2)pentagonal-pinch mode ofC60shifted to lower frequency. These results imply a strong interfacial interaction and charge transfer from the Ag to theC60.©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119106

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Here we report a strategy for the growth of single crystal heterostructures that dramatically reduces the nucleation of defects at the film–substrate interface. The substrate surface is patterned through miscut and passivated to enable a single domain template layer to be grown. This template is incommensurate with, and weakly bonded to, the substrate. A single domain film can then be nucleated preferentially at step edges and grown on the template. This mechanism is demonstrated for CdTe on Si(100) and should be applicable to many other systems. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119107

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Titanium–silicon–nitride films were grown by metal-organic chemical vapor deposition. At temperatures between 300 and 450 °C, tetrakis(diethylamido)titanium, ammonia, and silane react to form films with average compositions near theTiN–Si3N4tie line and low impurity contents(C<1.5 at. &percent;,H between 5 and 15 at. &percent;, with no other impurities present). The film resistivity is a strong function of Si content in the films, ranging continuously from 400 &mgr;&OHgr; cm for pure TiN up to 1 &OHgr; cm for films with 25 at. &percent; Si. Step coverages of approximately 75&percent; on 0.35 &mgr;m, 3:1 aspect ratio trenches, and 35&percent;–40&percent; on0.1 &mgr;m/10:1trenches are found for films with resistivities below 1000 &mgr;&OHgr; cm. These films are promising candidates for diffusion barriers in microelectronic applications. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119108

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Thermally grown Si(001)/SiO2samples were studied by x-ray reflectivity. Fits of model electron density profiles to the data reveal the existence of an interfacial layer at theSi/SiO2interface up to 15-Å-thick, with density higher than either the crystalline Si or the main oxide layer. This density of the layer is reduced by a postoxidation anneal. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119090

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Nanocrystalline GaN was synthesized through reactive laser ablation of gallium metal in aN2atmosphere. X-ray diffraction, selected-area electron diffraction, and transmission electron microscopy measurements show that the GaN crystallites are as small as 2 nm in diameter, and follow a log-normal size distribution with a mean particle diameter of 12 nm. Size-selective photoluminescence and photoluminescence excitation spectroscopy reveal a continuous range of blueshifted band-edge emissions and absorptions starting from the bulk value for gallium nitride and continuing to below 300 nm. These results are consistent with a GaN particle size distribution that encompasses regions above and below the excitonic-Bohr radius of GaN, such that the GaN material shows combined bulk and quantum confined optical properties. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119109

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

In this work, we demonstrate that the incorporation of carbon in the base of anpnSi/SiGe/Si heterojunction bipolar transistor dramatically reduces the outdiffusion of boron from the base under postgrowth implantation and annealing procedures. Without the addition of C, these processes would lead to transistors with vastly degraded transistor characteristics. This reduction in B diffusion, when compared to devices without C, has been observed by both secondary ion mass spectroscopy and improved electrical characteristics. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119110

出版商:AIP    

年代:1997

数据来源: AIP