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surate with that of high-quality closed- circuit television systems.

The user initiates his display request from his local keyboard. The computer then directs a display generator to build up the appropriate picture in a scan converter. The sequentially scanned output of the scan converter is transmitted over a video chan- nel and selectively received by the requesting console. A binary signal transition multi- plexing technique is used to record the received video signal on several tracks of a magnetic drum. The use of multiple tracks allows considerable improvement in resolu- tion over systems which use one track per picture. When the recording is completed, the scan converter can be cleared, and the computer, together with the display gener- ator, can respond to other requests. ,4t the local console the composite video signal is reconstructed from the drum storage and displayed on an ordinary television monitor.

A system was constructed which used three tracks of a magnetic drum to store the video signa!. The resolution achieved was essentially three times greater than if a single track had been used. The price per console is potentially quite low, as the display generator and scan converter costs are distributed over the large number of users.

3) The Defonnographic Storage Display Tube1-R. J . Hjohl, IBM Corp., A d - Danced Systems Development Division, Los Gatos, Calif. Employing a novel electrostatic configu-

ration, the deformographic storage display tube (DSDT) incorporates the fast point- by-point light-valve capability of the EidophorB technique and the two-sealed- chamber construction of the electrostatic storage display tube, an earlier IBM de- velopment. In the DSDT, a thin mica dia- phragm stores the charges written by the electron gun, while the resultant electro- static field deforms a transparent dielectric elastomer film cast on its other surface (in the second chamber). The optical phase image thus created is converted by a sepa- rate light source and schlieren optics into a large-screen projected image, which has high contrast and brightness. The DSDT technique permits selective erasure and update, or erasure by flood beam. Variable persistence provides image storage from 20 hours or more down to an erase time of 15 ms. The latter, in conjunction with 15 ms develop time, is equivalent to T V frame speed. Spot size of 2.5 mils has been mea- sured, with the expected limit around 1.5 mils. Sensitivity of <lo-' C/cm2 for writing permits recording a t T V scan speed.

The unusual versatility of the DSDT results from combining complete separation of storage and display functions, and light- valve operation, along with elastomer image- formation. Isolating the deformographic material from the electron beam permits use of oxide-coated cathodes in small sealed

contract with IBM Federal Systems Division, Oaego. 1 This work was supported in part by Air Force

s. Y.

tubes. With no phosphor to deteriorate, and with low cathode-loading and low ultor- voltage, long life and high reliability are expected.

4) Reflected-Light Pulsed-Laser Holog- raphy-F. J . McClung, A . D . Jacobson, and D . H . Close, Hughes Research Laboratories, Malibu, Calif. In this paper we present the results of

recent experiments with a high-performance stop-action holography system. The system is centered around a giant pulse ruby laser oscillator-amplifier combination that pro- duces 30-11s pulses containing up to 10 joules of energy. The exceptional property of this system is that the output is essentially fully coherent at full pulse energy. As a result, high-quality holograms can be made in reflected light from subjects that occupy a volume of several cubic meters. Holo- grams of diffusely reflecting subjects made with this system have consistently yielded reconstructions equal in brightness and image quality to the best gas-laser holo- grams. These results were obtained in spite of the fact that parts of the scene were mov- ing at velocities up to 10 m/s. In other words, successful reconstructions were ob- tained from parts of the scene which had moved through distances greater than one- half wavelength during exposure of the hologram.

The excellent coherence of this system results from the fact that the oscillator is operated in a single transverse and a single longitudinal mode. The high energy output of the system is achieved by amplifying the subject beam with a 12-inch long single-pass ruby amplifier. A description of the system is presented, as is a discussion of its operation and performance. A number of photographs of the reconstructions obtained from holo- grams made with the system are presented.

5 ) High-Contrast Solid-state Teletype Dis- play-E. Soxman and H. Herbert, Sigma- tron, Inc., Santa Barbara, Gal%?. This paper presents the results of a de-

sign study demonstrating the feasibility of fabricating an all-solid-state alphanumeric display terminal utilizing modular expand- able construction and ultra-high-contrast vacuum-deposited thin-film electrolumines- cent displays.

Provision is made for three lines, each line providing 80 alphanumeric characters, each character being generated by the selec- tive excitation of any combination of indi- vidual electroluminescent elements in a 35 spot (5x7) rectangular matrix. Recent state-of-the-art improvements in both func- tional lifetime and readability or contrast under high ambient lighting conditions are cited. Thousands of hours of display reada- bility under ambient illumination of several hundred foot-candles are indicated.

Discrete solid-state driver circuitry is included within the display panel case, which is approximately 4 inches high by 17 inches wide by 6 inches deep. Additional peripheral control circuitry, including logic, memory, addressing, and power supply is contained in a separate chassis of approxi- mately 24 f t3 .

Session 12-Solid-state Devices I1 : Bipola~, Transistors Chairman: F. &I. Smits Organizer: F. hl . Smits

1) High-speed High-Voltage n+-n Core Driver Transistor for Hybrid Technology -H. R. Gates and B. V . Gokhale, 1B.14 Corp., Hopewell Junction, N . Y. A transistor capable of switching l.?

amperes in less than 10 ns has been de\,el- oped for application in memory drive circuit,+ packaged using hybrid technology. The transistor was designed in glassed-chip form for high volume automatic handling, testing, and mounting equipment. One of the design goals was achievement of reliability without additional hermetic seals.

Theory for optimizing the design for two distinct applications is presented. Charge storage versus current density and collector-base bias was calculated numeri- cally for variations in doping profiles of epitaxial transistors plus variations in gold doping. The analysis generally supports the base stretching concepts introduced by C. T. Kirk. Sharply different behavior for gold-doped versus non-gold-doped devices was observed experimentally and predic.ted by the theory.

Optimum designs for two switching applications are presented. One device met the requirement for high gain and controlled switching time from a nonsaturated condi- tion. The other design met the requirements for minimum storage time from a heavily saturated condition. A noteworthy feature is the use of double level metallurgy-insu- lator technology. A new metallurgy system was developed to handle current densities in excess of 106A/cm2.

2) Avalanche Degradation of ~ F E - B . McDonald, FairLhild Semiconductor, Palo Alto, Ca1;f. When the emitter-base (EB) junction of

a silicon planar transistor is reverse bi,lsed beyond avalanche, the low current hFE of that device, under normal operating condi- tions, can be degraded by as much as 90 percent. I t will be shown that this avalanche stress causes a localized increase in the sur- face recombination velocity. If during nor- mal operation the emitter-base junction intersects the surface in the region of in- creased recombination velocity, hF8 is decreased. X o relationship was found to exist between this localized increase in surface recombination and oxide contamina- tion. The effect can be completely annealed in five minutes a t 300OC.

The above results were verified by using a gate-controlled transistor. This structure provides a means of studying the dependence of base current upon surface potential. Plots of base current versus gate voltage for fixed VEB were made before and after avalanche. The localized increase in surface recombina- tion resulting from avalanche stress mani- fests itself as a current peak in the accumu- lation region of the above plot.

Because of the variation of surface concentration of dopant in the planar emitter, the intersection of the EB junction