Jack H. Davis

Amorphous silicon photoconductor in a liquid crystal spatial light modulator

An amorphous silicon photoconductor has been demonstrated in a reflection mode nematic field effect liquid crystal spatial light modulator. The thin-film photoconductor provided high resolution of >35 lp/mm and sensitivity better than 20 microW/cm(2). In addition the switching speed was liquid crystal limited. Reported are the performance characteristics as well as a theoretical model for the device.

Liquid crystal spatial light modulator with a transmissive amorphous silicon photoconductor

A spatial light modulator with a thin (1-microm) amorphous silicon (PIN) photoconductor has been demonstrated with a threshold sensitivity of <3 microw/cm(2). A novel compound electrode design greatly increases the efficiency allowing the use of a photoconductive layer thin enough to achieve good transmission. The performance characteristics are reported and compared to the predictions of a theoretical model of the device.

Thermal expansion and Grüneisen parameters of InBi

Thermal expansion of InBi single crystals was measured over the temperature range 4.2−350 °K by dilatometry and x−ray diffraction. Unusually high anisotropy was observed; upon cooling, the samples expand in the c direction and contract perpendicular to c. α∥ is an order of magnitude more negative than the negative thermal expansion coefficients noted for other materials. The 300 °K thermal expansion coefficients (α⊥=60±5×10−6/ °K, α∥=−86±5×10−6/ °K) were used to calculate the following Gruneisen parameters for room temperature: γ∥=0.5±0.1, γ⊥ =1.5±0.2, and γ=0.7±0.1.

Measurement of nonlinear properties in Ag‐ion exchange waveguides using degenerate four‐wave mixing

Degenerate four‐wave mixing was used to evaluate third‐order nonlinearities in Ag‐Na exchange waveguides. Guided wave linear absorption analysis was used to correlate metallic Ag content with nonlinear properties. Measured conjugate reflectivities approached 4%.

The effect of thermal cycling on the resistance and morphology of InBi single crystals and polycrystals

Abstract The resistivity of single crystals of InBi has been measured at 295 K, 77 K and again after warming at 295 K. There was no evidence of hysteresis or morphology change. The apparent resistivity of polycrystals decreases with temperature but has an irreversible increase over the original room temperature value when warmed back to 295 K. Accompanying the increase of resistance with thermal cycling is the appearance of cracks on the surface of the sample, which may be explained by assuming that InBi has a large anisotropy in thermal expansion coefficients.

Growth of In2Bi Whiskers

The first compound whisker grown by squeeze technique (In2Bi) is reported. Rotating crystal x‐ray analysis and melting‐point measurements confirmed that the whiskers were In2Bi. The whisker axis coincided with the 〈001〉 direction for all four whiskers. A scanning electron microscope photograph indicates that the whiskers have diameters of a few μ and a morphology similar to tin whiskers.

GROWTH AND MORPHOLOGY OF InBi WHISKER CRYSTALS.

Abstract The growth of whiskers of compound InBi by the “squeeze technique” is reported. Rotating crystal X-ray analysis and melting point measurements confirmed that the whiskers were InBi. The whisker axis coincided with the direction for all three whiskers. Scanning electron microscope photographs indicate that the whiskers share the irregular cross section and ribbonlike morphology of other “squeeze-grown” metal whiskers.

Cleavage crystals of InBi

Abstract Filamentary crystals of InBi have been obtained by cleaving large single crystals. The InBi cleavage crystals are oriented along the a direction. These crystals break when subjected to bending tests but can withstand tensile stresses which produce strains up to 0.40±0.04%.