摘要:

A new evaporation procedure for preparing the surfaces of liquid crystal cells is described. It causes the liquid crystal to align uniformly, but with a small tilt bias. This is the optimum configuration for the important field effect display devices. The exact dependence of the orientation on processing parameters and the stability of the surfaces to high temperatures are described.

ISSN:0003-6951    

DOI:10.1063/1.88928

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

A high‐energy electron beam is generated using gas‐ionizing collisions to amplify a small cathode filament current. The technique makes use of a crossed magnetic and electric field to reduce the effective mean free path of electrons at the cathode. At a pressure of 5×10−5Torr helium, for example, a filament current of 0.4 mA will produce a uniform beam of 100 mA. Accelerating voltages up to 100 kV are used.

ISSN:0003-6951    

DOI:10.1063/1.88910

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

An experimental method is described which permits internal measurements of pressure and shear (IMPS) in shocked solids. The conceptual feasibility of the measurement was demonstrated by two experiments on polymethyl methacrylate (PMMA). The ability to make internal shear measurements raises interesting possibilities for shock‐wave studies in solids.

ISSN:0003-6951    

DOI:10.1063/1.88929

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Ion‐implantation damage has been used to getter impurities from semi‐insulating gallium arsenide. The gettered impurities are fast diffusers which move into the damaged layer during an anneal at 750 °C. Impurity profiles of epitaxial layers grown on the gettered surfaces after removal of the damaged material were used to evaluate the effectiveness of the gettering. The out‐diffusion of compensating impurities or defects from the substrate into the epitaxial layer during growth was greatly reduced by the ion‐implantation damage gettering. The same gettering effect was produced when either Ne+or Si+was used to create the damaged layer.

ISSN:0003-6951    

DOI:10.1063/1.88930

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Defect spatial distributions of extremely low concentration were measured, for the first time, by a transient capacitance technique in ion‐implanted MOSFET’s. Aluminum gate FET’s were ion implanted through the gate oxide with 1×1012of28Si+ions/cm2at 310 keV. The devices were annealed at 650 °C before Al was put down. Energy levels for the residual defects after annealing were obtained atEc−0.29,Ec−0.45,Ec−0.54, andEv+0.52 eV, respectively. Then the in‐depth distribution for each level was measured to a concentration of 1012/cm3by varying the gate voltage. The profile of defect distribution shows that the annealing after low‐dose implantation differs from the regrowth of the amorphous layer caused by heavy implantation and that most of the residual defects remain in the bulk rather than at the interface.

ISSN:0003-6951    

DOI:10.1063/1.88931

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Using the optical pumping method, laser oscillation was successfully achieved at 2 °K in indirect‐gap AlxGa1−xAs (x=0.46) implanted with nitrogen atoms for the first time. This shows that nitrogen isoelectronic traps in AlxGa1−xAs are effective for stimulated emission and laser oscillation, particularly in indirect material.

ISSN:0003-6951    

DOI:10.1063/1.88932

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Infrared radiation tunable from 5.5 to 18.3 &mgr;m was generated by difference frequency mixing in AgGaS2. The input sources were two tunable dye lasers, operating in the visible and pumped by a single N2laser. From the measured phase‐matching widths, the absorption of AgGaS2around 14 &mgr;m is calculated.

ISSN:0003-6951    

DOI:10.1063/1.88933

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Lasers in XeF, KrF, and ArF have been excited in a uv‐preionized transverse electric discharge. Laser pulse energies exceeding 100 mJ with peak powers of several megawatts have been produced with electrical efficiencies of over 1%.

ISSN:0003-6951    

DOI:10.1063/1.88934

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Laser action has been observed for the first time in ammonia subsequent to two‐photon absorption. Oscillation has been demonstrated in14NH3following two‐photon excitation by a pair of CO2TEA lasers operating on theP(34) andP(18) lines in the 10.4‐&mgr;m band, respectively. The observed wavelengths are 6.27, 6.69, 12.11, 13.72, 15.88, 15.95, 18.92, 19.55, 26.10, and 35.50 &mgr;m. Identification with existing spectroscopic information indicates that eight of the laser transitions occur within the &ngr;2manifold and originate by radiative pathways from the 2&ngr;2−(5,4) level at 2115.88 cm−1, whereas the remaining two, at 6.27 and 6.69 &mgr;m, take place in the &ngr;4mode. The usefulness of employing such lasers as sensitive probes for molecular collisional processes in excited vibrational levels is indicated.

ISSN:0003-6951    

DOI:10.1063/1.88911

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Laser‐drawn epoxy‐acrylate‐coated fused silica fibers (∼110 &mgr;m fiber diameter) have been produced with high and exceptionally uniform strength. When tested in 20‐&mgr;m lengths, they show a single‐moded Weibull distribution, (m∼25), a median tensile strengthSmof 750 ksi (5.25 GN/m2), and a coefficient of variation (&ngr;) of about 0.04. Using the previously justified ’’weakest link’’ model, this predictsSm∼600 ksi (4.2 GN/m2) for l‐km gauge lengths. The measured strength of a 1680‐m‐long fiber (i.e., the minimum strength found in testing 84 20‐m lengths) is 620 ksi (4.35 GN/m2). The capability of drawing kilometer lengths of fibers with strengths of this magnitude and uniformity is extremely important for the production of optical fiber cables.

ISSN:0003-6951    

DOI:10.1063/1.88912

出版商:AIP    

年代:1976

数据来源: AIP