摘要:

Silver colloids have been formed by ion implantation in float glass. Subsequent annealing methods alter the size distribution and optical reflectivity of the colloids. Furnace anneals and rapid flame heating convert large colloids into smaller units but excimer laser annealing appears to cause a dissolution of silver into the glass network.

ISSN:0021-8979    

DOI:10.1063/1.354194

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

The surface versus bulk composition and electronic structure of polycrystalline CuInSe2thin‐film interfaces were studied by synchrotron radiation soft‐x‐ray photoemission spectroscopy. Ann‐type In2Se3/CuIn3Se5surface layer forms on enhanced‐grain polycrystalline thin‐filmp‐type CuInSe2during fabrication. Enhanced‐grain CuInSe2films were sputter etched (500 V Ar) and analyzedinsituto determine core‐level binding energies and Fermi‐level positions for then‐type surface and thep‐type CuInSe2bulk within ±0.1 eV. The transition between then‐type surface and thep‐type bulk was experimentally observed by noting the change in the position of the valence‐band maximum relative to the Fermi levelEF. From these measurements, the valence‐band offset &Dgr;Evbetween the layers was determined to be 0.50 eV. Measurement of the work functions &fgr; was also completed and reveals &fgr;=4.75 eV for the In2Se3(CuIn3Se5) surface layer and &fgr;=4.04 eV for the bulk CuInSe2. Combining these results allows construction of a surface band diagram for this device configuration as well as determination of the relationship between composition, electronic structure, and device performance.

ISSN:0021-8979    

DOI:10.1063/1.354195

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

A general model and analytical results have been derived to obtain laser‐induced temperature rise in substrates with periodic multilayer structures. The substrate can be equivalent to a homogeneous substrate with anisotropic thermal conductivity, if the dimension of the periodic structure is much smaller than the laser spot size. The laser‐induced temperature rise can be then obtained by solving the three‐dimensional heat equation with the different thermal conductivities in directions parallel and perpendicular to the layer structure. This model has been applied to calculate the laser‐induced temperature rise in Si and Mn–Zn ferrite composite materials. A different temperature rise can be obtained when a laser beam irradiates the substrate surface, which is oriented in parallel or perpendicular to the layer structure.

ISSN:0021-8979    

DOI:10.1063/1.354196

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

The technique of laser‐assisted molecular‐beam deposition (LAMBD) has been used to fabricate a molecular film by reaction in a molecular beam. Molecular iodine vapor entrained into a stream of helium carrier gas was introduced via a supersonic expansion into the plasma plume of laser‐evaporated copper to produce copper iodide. Films were deposited on substrates that were situated about 3 cm downstream on the path of the molecular beam. The surface morphology of films depends greatly on the fluence of the incident laser beam and expansion conditions. Films grown at low laser powers show small surface inhomogeneities in their electron micrographs compared to the films that were grown at higher laser powers. Copper in the LAMBD films is found to be mainly in the Cu+1state as characterized by electron spectroscopy for chemical analysis. A comparison of the surface and structural properties of LAMBD films with that of a vacuum‐evaporated film suggests that both films have similar lattice structures and compositions. It seems that LAMBD can be a powerful technique to deposit novel molecular and composite films for electronics and photonics.

ISSN:0021-8979    

DOI:10.1063/1.354197

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

Laser‐induced plasmas obtained during a welding process have been studied. Spectroscopic diagnostics and an integrating sphere collecting the reflected CO2light are the principal diagnostics used in order to determine the spatial variations of the microscopic parameters such as electron density and temperature, and the energy absorption during this process. For several experimental processing conditions of shielding gases, the main perturbing effects such as absorption and refraction of the CO2laser radiation are quantified. Several possibilities for reducing these perturbing effects are then discussed.

ISSN:0021-8979    

DOI:10.1063/1.355284

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

A new laser method is proposed for the deposition of high purity, hard fcc TiN layers of unlimited thickness. The film thickness can be very finely controlled mainly through the intermediary of the number of applied laser pulses as the deposition rate is of only 0.02–0.05 nm/pulse. The ablation is promoted from a Ti target by high intensity multipulse excimer laser irradiation in a low pressure N2ambient gas while the forming compound is collected on a Si single‐crystalline wafer. The best results have been obtained for an ambient pressure ofp=10–30 mTorr and a distance between the target and support ofd=10 mm. It is shown that the formation of a liquid phase within the irradiated zone, maintained even after the end of a laser pulse, is the most important requisite for TiN formation. TiN is then ablated as a stoichio‐ metric phase.

ISSN:0021-8979    

DOI:10.1063/1.354198

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

Polymerization of a mixture of C60/C70in rf plasma is reported. The electric dark‐current conductivity of the plasma‐polymerized mixture of C60/C70, which is approximately 10−7S/cm in the atmosphere, does not depend on the applied voltage at least in the range of −25 to 25 V. A semiconductor‐type temperature dependence of the conductivity in the higher‐temperature domain was observed, and the band‐gap energy was estimated to be 2.1 eV. The conductivity increased with increasing temperature from 25 to 230 °C in vacuum, whereas in the atmosphere the conductivity increased upon decreasing the temperature below 80 °C. It is supposed that in this temperature domain the electric conductivity is enhanced by the existence of water molecules on the film, the surface of which is characterized by a high hydrophilicity. The surface morphology of the polymerized film was characterized by the presence of aggregates with diameters of about 300 A˚ and the surface was highly hydrophilic, polar, and heterogeneous. The surface has a completely amorphous molecular structure. When the C60molecules polymerize each other, it has been shown that the polymerization of C60molecules proceeds, at least primarily, by the formation of 1,2‐cyclobutane structures between the cyclohexatrienyl parts of neighboring C60molecules. The addition of hydrogens, hydroxyl groups, carbonyl groups, and aryl peroxide groups to the radical sites occurs but the free radicals of the order of magnitude 1017spins/g were found to remain without quenching.

ISSN:0021-8979    

DOI:10.1063/1.354199

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

The thickness dependence of selectively deposited Si1−xGexon the oxide pattern defining the deposition is a strong function of the total system operating pressure. The pattern sensitivity is much greater for atmospheric‐pressure deposition than for reduced‐pressure (10–80 Torr) deposition. Within the reduced‐pressure regime, the pattern sensitivity decreases as the pressure is reduced, either for the same GeH4mole fraction or for the same Ge content in the deposited layer. The observed behavior is consistent with the easier lateral transport of reactive species in the gas phase at lower pressure. Higher HCl mole fractions also decrease the pattern sensitivity.

ISSN:0021-8979    

DOI:10.1063/1.354200

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

The growth of diamond in a subatmospheric dc‐arc plasma‐jet reactor has been studied theoretically. Full transport equations for this geometry, including gas‐phase and surface chemistry, have been solved numerically. The surface‐reaction mechanism includes pathways for the incorporation of CH3, C2H2, and C from the gas phase, as well as growth of graphite. The surface mechanism includes full reversibility for all reactions, based on estimates of the thermochemistry. Results are presented for degrees of dissociation of H2in the plasma gun ranging from 2.6% to 90%, and inlet levels of CH4spanning 0.1–5.0 mol %. It is seen that CH3is the predominant growth species when there is little H2dissociation within the plasma gun, but C becomes the dominant species at higher dissociation levels. The third growth species, C2H2, does not play a role in diamond growth under these conditions when there is less than 1% CH4in the feed; but, at higher CH4levels both C and CH3addition rates drop to 50 times greater than C2H2.

ISSN:0021-8979    

DOI:10.1063/1.354201

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

A special test structure consisting of a box‐shaped boron profile capped by a lightly doped arsenic layer has been used to determine that extended defects absorb some of the interstitials injected during a wet thermal oxidation. Reduced oxidation‐enhanced diffusion of the boron layer is observed for samples containing the extended defects. Secondary ion mass spectrometry measurements are combined with transmission electron microscopy measurements to calculate theDIC*Iproduct which is found to be in good agreement with values previously obtained from gold diffusion experiments. In addition, a lower bound on the ratio of the net number of silicon atoms injected during the oxidation to the number of silicon atoms consumed is calculated. A one‐dimensional model for the growth of the extended defects has been implemented intosuprem‐iv. Simulations with the new model agree with experimental data. The growth of the extended defects is also shown to be a reaction‐limited process.

ISSN:0021-8979    

DOI:10.1063/1.355306

出版商:AIP    

年代:1993

数据来源: AIP