Showing papers by "Energy Conversion Devices published in 1974"

Photostructural transformations in amorphous As2Se3 and As2S3 films

Abstract: The influence of illumination and annealing on thin films of amorphous As2Se3 and As2S3 has been studied through their effects on the structure and optical properties. It is shown that the dominant photostructural change in evaporated films is the polymerization of the as-deposited molecular (As4S6 or As4Se6) glass through either illumination or heating. This irreversible polymerization gives rise to a large absorption edge shift to smaller energy and to an appreciable index of refraction change. In addition there is a small reversible absorption edge shift, due presumably to trapping of photo-generated electrons and holes which is larger in As2S3 than in As2Se3. This reversibility persists in both well-annealed evaporated films and in sputtered films which appear to be structurally indistinguishable both from each other and, aside from defects or voids, from the bulk glass. The reversible effect, called photo-darkening, is accompanied by a negligible refractive index change when compared with the irreversible polymerization change. The application of the present results to photochemical effects is discussed.

Dry process production of archival microform records from hard copy

Abstract: A dry-process method and apparatus for producing archival microform records from light reflecting hard copy utilize a dry-process mask film strip which is photosensitive to and microimaged by light reflected and reduced or condensed from the hard copy and developed by heat to provide microimaged transparencies therein as the mask film strip is moved to an imaging and developing station. It also utilizes a dry-process microform film which has archival properties and which is sensitive to and microimaged and developed by short pulses of electromagnetic energy above a threshold value applied thereto through the microimaged transparencies of the superimposed mask film strip when it is moved to an image transferring station to provide in the microform film imaged microform records which conform to the transparent microimages in the dry-process mask film strip and, hence, the hard copy and which have achival properties. The microform film is preferably in the form of a microfiche.

Structure and method for producing an image

Abstract: A new structure comprising a layer of an imaging material, capable of undergoing an image forming change in response to energy, a layer of a barrier material and a layer of a catalyst material which, if necessary after activation, is capable of causing or promoting the image forming change in the imaging material The barrier material is capable of controlling in accordance with a desired image pattern, the passage of the catalyst material through the barrier layer into contact with the imaging material in selected areas, while it prevents passage of the catalyst material in other selected areas The permeability of the barrier layer for the catalyst material and, if necessary the activation of the catalyst material, may be controlled by the selective imagewise application of imaging energy to the structure, and the image forming change in the imaging material may be brought about by the application of development energy, such as heat, to the structure to produce a detectable image in the layer of the imaging material

Study of the optic modes of Ge 0.30 S 0.70 glass by infrared and Raman spectroscopy

Abstract: A study of the room-temperature infrared reflectance and Raman spectra has been made on a ${\mathrm{Ge}}_{0.30}$${\mathrm{S}}_{0.70}$ glass. The dominant features of the two spectra are complementary with respect to frequency, and can be understood in terms of a molecular model in which the Ge atoms are fourfold coordinated and S atoms twofold coordinated; the molecular structure in the model is a Ge${\mathrm{S}}_{4}$ tetrahedron. Splittings of the bond-stretching modes into two components provide a measure of the intermolecular coupling. Density-of-states effects are clearly present in the low-frequency portions of the spectra, particularly in the Raman spectrum where the bond-bending optic modes and acoustic modes contribute to a continuum of scattering.

Method and means for preventing degradation of threshold voltage of filament-forming memory semiconductor device

Abstract: The number of set and reset cycles to which a filament-type amorphous memory switch device can be operated without threshold degradation is found unexpectedly to be a function of reset current pulse width, the number of reset current pulses used to effect each resetting operation and the spacing of the reset current pulses. In one case, for low current reset, it was determined each reset operation should comprise a burst of at least about 10 and preferably about 50-150 reset current pulses to effect homogenization of the reset filament, each reset current pulse should be substantially under 10 microseconds in width, and the pulse spacing should be substantially less than the threshold recovery period of the memory switch device, preferably much less than 10 microseconds. Such a burst of a large number of reset current pulses are particularly useful in setting memory switch devices in very low current rated circuits. In such case, the initial low amplitude reset current pulses fully reset the filament path and the following low amplitude reset current pulses homogenize the filament path.

Mössbauer Spectroscopy of 125Te — Some New Results and Applications

Abstract: Narrow and reproducible linewidths for the 35.5-keV Mossbauer resonance in 125Te have been observed with a 2.7-year 125Sb source diffused in Cu. Measurements made on cubic ZnTe as a function of absorber thickness reveal that the linewidth of these sources is Γsource = 5.20 ± 0.08 mm/sec. This result is in good agreement with the minimum observable line-width 2Γnat as calculated from the measured half-life of the 3/2 level, t½ = 1.475 ± 0.010 nsec. From this Mossbauer measurement the Debye temperature of cubic ZnTe is found to be 175 ± 9 °K. The Mossbauer effect in 125Te provides a useful technique for characterizing amorphous chalcogenide semiconductors. Investigations on sputtered thin films of amorphous GexTe1-x were performed as a function of composition, temperature, and heat treatment. The variation of the quadrupole splitting as a function of composition exhibits discontinuities in slope at x = 0.33 and 0.50. These results are indicative of chemical ordering in the amorphous GexTe1-x system at these compositions. A structural model of amorphous GexTe1-x alloys based on two inequivalent Te sites is developed for the Te rich phase and is found to fit the data well. Annealing of the films is shown to lead to a greater degree of structural order on a microscopic scale. Crystallizing the films is shown to lead to phase separation of the system into crystalline GeTe and Te metal.