摘要:

Lattice strain due to boron in silicon epitaxial wafers has been measured by the x‐ray double‐crystal technique. It is found that the lattice strain depends on the crystal orientation and that the strain for (100) is about 1.3 times larger than that for (111). The results for (111) lead to a lattice contraction coefficient for boron &bgr;=8×10−24cm3/atom, which is 1.5–4 times larger than previous values obtained with diffused (111) wafers.

ISSN:0003-6951    

DOI:10.1063/1.88879

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The enhancement of cw laser melt‐through of solids resulting from melt removal produced by a blowoff impulse generated by short superimposed laser pulses is investigated. A simple model is used to develop an expression for the minimum impulse criteria.

ISSN:0003-6951    

DOI:10.1063/1.88864

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Motivated by recent advances in the production of intense ion beams, we consider the possible utility of such beams for heating a long thin &Vthgr;‐pinch plasma to thermonuclear temperatures. It is found that ion beams offer an alternative to previously proposed schemes utilizing CO2laser beams and intense relativistic electron beams.

ISSN:0003-6951    

DOI:10.1063/1.88874

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

In monatomic plasmas excited by high‐intensity relativistic electron beams, the electron secondary distribution function is dominated by elastic electron‐electron collisions at low electron energies and by inelastic electron‐atom collisions at high electron energies (above the excitation threshold). Under these conditions, the total rate of excitation by inelastic collisions is limited by the rate at which electron‐electron collisions relax the distribution function in the neighborhood of the excitation threshold. To describe this effect quantitatively, an approximate analytic solution of the electron Boltzmann equation is obtained, including both electron‐electron and inelastic collisions. The result provides a simple formula for the total rate of excitation.

ISSN:0003-6951    

DOI:10.1063/1.88885

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The correct prediction of the electronic stopping power is important in establishing the basis for the technique of ion bombardment of neutron damage. Experimental measurements of the stopping power and the depth distribution of damage deposition by heavy atomic projectiles incident on matter have shown that the velocity proportional electronic stopping power formulas of Lindhard and Firsov are not valid for projectile velocities in the range from 2v0up tov1, wherev0is the Bohr velocity andv1is Lindhard’s proposed upper limit for the validity of these formulas. This letter points out that a previously published modification of the Firsov theory predicts a strong superlinear dependence of the stopping power on velocity in this velocity region due to effects which arise when the incident projectile velocity is comparable with that of the atomic electrons. Apart from a scale factor along the velocity axis, which must be determined from experimental measurement, the modified theory correctly predicts the energy dependence of the low‐energy electronic stopping power. Values of the scale factor for a large collection of projectile‐target combinations indicate that for most projectile‐target combinations the velocity‐proportional region of the electronic stopping power does not extend abovev0.

ISSN:0003-6951    

DOI:10.1063/1.88875

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The origin of a large spread in the activation energy of crystallization, &Dgr;E, in metallic glasses is explained based on a structural relaxation model. The calculated &Dgr;Efrom the available thermal and viscosity data is in fair agreement with the experimental results. It is the structural relaxation which leads to high &Dgr;E(⩾100 kcal/mole) for stable glasses. It is also suggested that the structural relaxation is the rate‐controlling factor during the crystallization of the unstable glasses. Thus &Dgr;Efor unstable glasses is low (&Dgr;E⩽20 kcal/mole), and is expected to be lower for amorphous metals prepared by low‐temperature deposition than for the corresponding melt‐quenched metallic glasses.

ISSN:0003-6951    

DOI:10.1063/1.88876

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Measurements are presented of absolute sputtering coefficientsSfor polycrystalline Au bombarded by 45‐keV ions withZionranging from 2 to 79. Low‐fluence results taken with chemically etched Au surfaces represent the first complete set ofSvalues taken under the nearly ideal sputtering conditions of vanishingly small ion fluence and undamaged target surface. The results confirm unambiguously the smooth monotonic increase inSwithZionas predicted by sputtering theory. High‐fluence results are also obtained which are representative of implanted‐target surface conditions. These results exhibit the periodic variation ofSwithZionas seen in past sputtering investigations.

ISSN:0003-6951    

DOI:10.1063/1.88877

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

In1−xGaxP1−zAszdouble heterojunctions (77 °K, yellow) are shown to exhibit either (or both) homogeneous or inhomogeneous line broadening when operated as lasers in an external grating cavity. Just above threshold, inhomogeneous line broadening is observed over much of the recombination spectrum. Well above threshold (large gain), homogeneous line broadening is observed when the grating is tuned onto the cavity modes in the region of line center.

ISSN:0003-6951    

DOI:10.1063/1.88878

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Sputter deposition of low‐resistivity (0.02 &OHgr; cm) layers of SnO2‐doped In2O3onto AlxGa1−xAs results in heterojunction barriers to eithern‐ orp‐type material. Low‐loss AlxGa1−xAs waveguides with SnO2‐In2O3cladding have been fabricated. Their propagation properties can be efficiently modulated by means of the linear electro‐optic effect. Phase shifts for TE modes of 160 deg/V cm were measured at a wavelength &lgr;=0.9 &mgr;m.

ISSN:0003-6951    

DOI:10.1063/1.88880

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Operation of a new cleaved facet room‐temperature double heterostructure GaAs:GaAlAs laser utilizing leaky wave coupling through the substrate is reported. The coupling mechanism is analogous to that of prism coupling from a waveguide, but no external components are used. The laser produces a highly collimated output beam with approximately 2°×8° divergence. The peak pulsed beam power at 2 times threshold is 1.5 W from one end with approximately one‐third of this power in the collimated beam. The total external differential quantum efficiency is on the order of 35%. These desirable characteristics are obtained at the expense of threshold current increases of approximately 30%.

ISSN:0003-6951    

DOI:10.1063/1.88881

出版商:AIP    

年代:1976

数据来源: AIP