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61.
The redistribution of boron profiles in bulk silicon and SOS (silicon-on-sapphire) type structures is investigated in this paper. Experimental data on thermally redistributed profiles are correlated with predictions based on a computer program whose numerical algorithm was described in an earlier paper. Three cases were considered which involved the thermal redistribution of 1) a high dose (2×1015 and 5×1014 cm–2) 80keV boron implant in (111) bulk silicon, in an oxidizing ambient of steam at 1000°, 1100°, and 1200°C, respectively; 2) a high dose (2.3×1015 cm–2) 25 keV boron implant in (100) silicon-on-sapphire, in a nonoxidizing ambient of nitrogen at 1000 °C; and 3) a low dose (3.2×1012 cm–2) 150 keV boron implant in (100) bulk silicon, in oxidizing and nonoxidizing ambients that make up the fabrication schedule of an-channel enhancement mode device. For all three cases the overall correlation of computer predictions with experimental data was excellent. Correlations with experimental data based on SUPREM predictions are also included. 相似文献
62.
The electronic structure of the (111) surface of aluminum is calculated using self-consistent pseudopotentials. Surface states are identified and the (111) work function calculated. The behavior of the total charge density and potential near the surface is displayed and discussed. Self-consistency is found to be of crucial importance. 相似文献
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We show that orbital energies from existing hybrid functionals do not give reliable band gaps. Even if a functional yields a good bulk gap, it in general does not provide accurate gaps in different structural configurations, e.g., surfaces or nanostructures. For example, none of the popular hybrid functionals adequately describe the surface-state gap of the Si(111)-(2 × 1) surface. For graphene nanoribbons, some hybrid functionals give good optical gaps (neglecting strong excitonic effects), but not quasiparticle gaps. In both cases, there are strong variations from different hybrid functionals. 相似文献
66.
M.J. Losty V. Chaloupka A. Ferrando L. Montanet E. Paul D. Yaffe A. Zieminski J. Alitti B. Gandois J. Louie 《Nuclear Physics B》1974,69(1):185-204
A modified Chew-Low extrapolation procedure is applied to the reaction π?p→Δ++π?π? to extract the I = 2 ππ elastic cross sections from threshold to 1260 MeV. The predictions of the one-pion-exchange model are used to estimate the contributions from background processes of the type π?p→Δ0?0. The moments of the π?π? angular distribution are also extrapolated to the pion pole and a phase shift analysis performed. The s-wave inelasticity is constrained using information on the inelastic cross section coming from six-body final states. The magnitude of the s-wave phase shift at the K0 mass is found to be 7.20 ± 1.00, increasing to 26.20 ± 2.50 at 1 GeV. d- and g-waves contribute above about 900 MeV, but the corresponding phase shifts are small compared with the s-wave. All three phase shifts have the same sign. 相似文献
67.
Work done by the snow skier during pumping and rocking the center of mass can result in significant accelerations. Pumping and rocking strategies maximizing the velocity of a particle over undulating snow surfaces have been investigated in this paper. The prescribed motions included translation of the particle mass radially from a point contact with the snow surface and rocking of the point contact forward and backward in the vertical plane. The mechanics of the induced velocity variations and the expected magnitude of the velocity variation were of primary interest. The equations of motion were integrated numerically to determine skier-ski model velocity. Positive and negative variations in velocity from 10% to 100% were predicted with pumping strategies over distances of 10–15 m. 相似文献
68.
Electron-phonon (e-ph) renormalization effects in a model cuprate system CaCuO2 are studied by employing density functional theory based methods. Whereas calculations based on the local spin-density approximation (LSDA) predicts negligible e-ph coupling effects of the half-breathing Cu-O bond stretching mode, the inclusion of a screened on-site Coulomb interaction (U) in the LSDA+U calculations greatly enhances the e-ph coupling strength of this mode. The full-breathing mode, on the other hand, shows a much weaker e-ph renormalization effect. 相似文献
69.
Recent scanning tunneling microscopy studies of individual organic molecules on Si(001) reported negative differential resistance (NDR) above a critical applied field, observations explained by a resonant tunneling model proposed prior to the experiments. Here we use both density functional theory and a many-electron GW self-energy approach to quantitatively assess the viability of this mechanism in hybrid junctions with organic molecules on Si. For cyclopentene on p-type Si(001), the frontier energy levels are calculated to be independent of applied electric fields, ruling out the proposed mechanism for NDR. Guidelines for achieving NDR are developed and illustrated with two related molecules, aminocyclopentene and pyrroline. 相似文献
70.
Wang Y Yamachika R Wachowiak A Grobis M Khoo KH Lee DH Louie SG Crommie MF 《Physical review letters》2007,99(8):086402
STM studies on K(x)C(60) monolayers reveal new behavior over a wide range of the phase diagram. As x increases from 3 to 5 K(x)C(60) monolayers undergo metal-insulator-metal reentrant phase transitions and exhibit a variety of novel orientational orderings, including a complex 7-molecule, pinwheel-like structure. The proposed driving mechanism for the orientational ordering is the lowering of electron kinetic energy by maximizing the overlap of neighboring molecular orbitals. In insulating (metallic) K(x)C(60) this gives rise to orbital versions of the superexchange (double-exchange) interaction. 相似文献