This is PAGE 1 of the 1960s exhibit. Go here for PAGE 2.

1960-1969: THE LED IS BORN

For a really great lesson about very early LEDs, go here, then keep reading here. :)

Another article about the invention of the LED that you may want to read is right here.

		Our first exhibit: An example of technology used in the very first Light Emitting Diode ever mass-produced for industry and consumer. First appearing around 1969, this technology was actually available as early as 1962 but at that time only as a rather expensive and rare laboratory curiosity. Early models came in tiny metal cans with a clear window, bubble, or lens on the end. This model is obviously newer. This breakthrough model emitted infrared light, which is essentially invisible to the human eye. Fortunately for us, a variety of technology exists today which can capture this invisible light for old time's sake. Shown under the LED is one way of doing that: a chemically doped card that converts infrared into an orangish glow us humans can see. Video & digital cameras are also usually sensitive to this kind of invisible light. Chemically, this LED consists of the compound Gallium Arsenide; which is the metal gallium and the element arsenic, familiar to some of you as an older type of mouse & rat poison. Put two and two together, and you have the world's first completely solid-state, cold light source. Thus, the LED was born.

This is how the LED would look to you if you could see infrared light. Here, the camera, sensitive to the 950nm wavelength, shows you the rather unusual double-whisker design of this early LED. An LED like this was probably first used in factory machinery for object detection; an upgraded version of this LED eases our daily lives, living in our TV and VCR remote control units and as sensors in all kinds of products we use every day.

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		Arguably, this is likely one of the first visible red LEDs to surface. Appearing around mid 1969, this Monsanto MV2 red LED was purchased in London at a military surplus store on Tottenham Court Road. It originally cost ?1, at a time the typical wage earner made ?7 a week. So it was not cheap. As you can see by the picture, this came in a metal can with a glass or acrylic bubble on the business end. This LED has a very unusual chip construction, consisting of a gallium arsenide substrate (the base material) with a gallium arsenide phosphide emitting layer, and has a metal contact ring serving as the 1960s counterpart to today's gold bond ball. The actual light emitting surface is a circular region inside this ring, as shown in the picture. A small amount of red light also emenates from the vertical surfaces of the chip substrate; this is splotchy and irregular and is probably some GaAsP "overspray" of sorts from what was then a crude (by today's standards) manual manufacturing process. Chemically, this LED consists of the compound GaAsP on a GaAs substrate. When unlit, the color of the chip is a jet black. The anode ring is probably platinum, rhodium, or other nonreactive rare earth metal; and the rest of the metal components inside the LED are gold plated. Thanks to David Chambers in Scotland for hanging on to this LED for thirty plus years.

From the user called, "mediatechnology" on Pro Audio Design forums, come these paragraphs from Monsanto (no changes to grammar or syntax were made) about these LEDs:

"Until 1968, visible and infrared LEDs were extremely costly, on the order of US $200 per unit, and so had little practical use. The Monsanto Company was the first organization to mass-produce visible LEDs, using gallium arsenide phosphide in 1968 to produce red LEDs suitable for indicators. Hewlett Packard (HP) introduced LEDs in 1968, initially using GaAsP supplied by Monsanto. The technology proved to have major uses for alphanumeric displays and was integrated into HP's early handheld calculators."

"Film Annotation Using The LED" By definition, annotation means to make or furnish critical or explanatory notes or comment. Conventional methods of film annotation such as the neon lamp, spark gap or gas discharge systems left the instrumentation engineer with much criticism and little explanation/information on his film. The light emitting diode LED will solve this problem because of its many advantages over the past methods used in film annotation. The most common use of the LED in photo instrumentation is the annotation of time and/or event marks on the edge of the film. This GaAs Lite Tip will discuss the advantages of the LED and the types of film recommended tor use with the LED."


Spectrographic analysis of the above LED.



Same as above; newer spectrometer software & settings used.
USB2000 spectrometer graciously donated by P.L.

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Closeup of Monsanto MV2 red LED similar to the one shown above.
Pink color in the photograph is not the actual color of the emitted light.
Photo courtesy of Paul Schick



I also tried taking a picture of one of these.
The severe distortion is from the LED's lens.



TOP (or left): Another MV2 LED closeup with the LED not powered.
BOTTOM (or right): Same LED viewed from a more typical angle and receiving a *very* small current.
Photos courtesy of Paul Schick




This is the die of a red LED that otherwise looks just like the MV2. I haven't seen a top ohmic contact like this in an older LED; though some of the newest Luxeon Star emitters have begun to use something similar. Most of this LED's light is emitted through those five skinny dark slots on top of the die.



This is PAGE 1 of the 1960s exhibit. Go here for PAGE 2.





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