April 1960 Popular Electronics
People old and young enjoy waxing nostalgic about and learning some of the history
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transistorized i.f. stage for a TV set can be built today to fit
into a match box. But molecular electronics has made possible the
production of a device that contains two such stages and is only
a fraction of the size of a single transistor!" Nobody talks of
molecular electronics today, but that really is an accurate term
for what we have when compound semiconductors like GaAs, GaN, or
any of the many-atomed exotic photovoltaic substrates are being
discussed. When referring to pure elements like silicon that are
being doped with impurities, I'm not sure those structures are considered
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By J. K. Locke
a press conference in Washington recently, a demonstrator connected
an ordinary phonograph to a pair of tiny wafers that fitted easily
into the palm of his hand. Then he hooked two leads from the wafers
to a 15" loudspeaker. When he flipped a switch, music filled the
The two little discs that did the man-sized
job of amplifying the weak signal from the record player into a
hefty five watts of power are striking examples of some of the first
triumphs of "molecular electronics," a startling new design concept
that promises to revolutionize the entire electronics industry.
Molecular electronics is not just a new advance in
miniaturization. It is a radically different approach to electronic
design that provides amplifiers, oscillators, and other complete,
operating electronic circuits without tubes, transistors, resistors,
or capacitors. Five full watts
power can be obtained from the molecular electronic amplifier at
left. In actual use, the tiny unit is installed in a heat sink (black
casing in lower photo). Smaller unit in demonstrator's hand is a
preamplifier. The amplifying system has an overall response from
0 to 20,000 cps. Comparison
electronic power converter with conventional circuit. In the molecular
circuit, one block of material does the entire job of rectification
and filtering. Heat produced by passage of 110-volt alternating
current through the resistive domain (top layer) is transferred
by the electrically insulating center layer to the bottom layer,
which is composed of a thermoelectric material.
A five-watt audio amplifier less than the size of a dime and
a two-stage video amplifier much small still... these are among
the first products of an exciting new era, the age of Molecular
Size reference of IC.
Multiple junction systems
attached to the dendritic
ribbon above are complete multivibrator circuits smaller than
the point of a pencil. These are some of the first molecular
electronic circuits to be produced by entirely automatic machinery.
Engineers hope that complete amplifiers, radios, and other more
complex circuits will soon be produced automatically.
greatly simplifies circuitry.
A conventional transistorized circuit for a light telemetry
subsystem is shown in upper diagram above, with the equivalent
molecular electronic circuit below it. Fewer components and
fewer soldered connections will increase reliability of equipment.
Unit in photo is the actual molecular electronic telemetry subsystem.
Although molecular electronics is hardly out of the laboratory,
it is already clear that equipment using its principles will be
far smaller, lighter, more reliable, and ultimately cheaper than
anything available today. One example will illustrate its advantages.
A transistorized i.f. stage for a TV set can be built
today to fit into a match box. But molecular electronics has made
possible the production of a device that contains two such stages
and is only a fraction of the size of a single transistor! . And
the molecular electronic unit operates on only a fraction of a volt
- much less than the power required for transistors.
As far as complexity is concerned, a transistorized circuit has
perhaps a dozen components and 35 soldered connections, while a
comparable molecular electronic circuit only has about two parts
and four connections. Integrated Circuitry.
The concept of molecular electronics was developed during the search
for better ways to miniaturize electronic equipment. While great
strides had been made in designing smaller and smaller individual
components, it was obvious that far greater miniaturization and
reliability could be achieved if all the necessary electronic properties
could somehow be built into a single, solid block of semiconductor
As solid-state physicists gained better
understanding of the structure of materials and the flow of electrical
charges in them, it became possible to design simple "function blocks"
containing, for example, both capacitance and resistance. Later,
n- and p-type materials were added to produce amplification as they
do in transistors and tunnel diodes. Finally, scientists were able
to produce single bits of material that would function as complete
The various electrical properties
such as resistance, capacitance, and amplification are not localized
in anyone spot in these function blocks. They are, instead, distributed
throughout the material. Molecular function blocks - even those
as complex-looking as the five-watt audio amplifier with its concentric
rings - are not put together from a number of different parts. Instead,
they are cut from a single tiny chunk of semiconductor material.
The block is then etched, alloyed and treated until the desired
results are obtained. Automatic Production.
Engineers are working on the design of machines that will turn out
completed circuits automatically. Although only the simplest circuits
are now produced by automatic machines, great strides have been
made. For example, a method of drawing ribbons of semiconductor
material called "dendrites" directly from the molten mass has already
been perfected. These ribbons are of exact size and thickness, with
optically perfect surfaces. They are practically ready for use as
they emerge from the furnace, and there are virtually no rejects.
By contrast, semiconductors are normally made in the form
of ingots which must be x-rayed, oriented, sawed, lapped, etched,
and polished before they are ready to use. In addition, this "old"
method results in a high percentage of rejects.
dendritic ribbon to which tiny multiple-function systems have been
automatically attached is. Here a series of multivibrators has been
created directly on the dendrite. The individual circuits need only
be clipped apart and leads attached. Soon, complete amplifier circuits
will be produced the same way. The dendrite ribbon will be snipped
into different lengths to give amplifiers of different gains - the
longer the strip, the greater the amplification!
engineers hope to "grow" complex electronic equipment - complete
receivers, for example - automatically and continuously from a pool
of semiconductor material. These receivers are still far in the
future, but they would be unbelievably cheap and trouble - free
by today's standards. Because of the low power consumption of molecular
electronic function blocks, a single battery would last for years.
As might be expected, the first application
for molecular electronics will be in the military and space fields.
The savings to be realized in weight, size, and power consumption
are of paramount importance here.
Of even greater
significance is the tremendously improved reliability that can be
achieved through the use of these amazing devices. To see why, consider
the example of a giant rocket designed for hurling our satellites
into orbit .
The rocket's electronic "innards" are
made up of 20 or 30 thousand separate parts and perhaps 75 thousand
connections. If just one of these parts or connections fails, we
suffer another missile failure. With molecular electronic equipment,
only one-tenth to one-twentieth the number of parts and connections
is needed. Consequently, there is much less chance that a part or
connection will go bad under strain, and the promise is that missile
firings will be far more successful than ever before.
electronic units for military use are now being developed by Westinghouse
under a U.S. Air Force contract. Although it takes time to design
and test circuits, set up production lines, and train personnel,
the first of these units will be going into action within about
three years. Consumer Use.
hard to say when molecular electronic products will be available
for the consumer market. But it is a certainty that such devices
will be on sale some day. Because they will be produced by continuous,
automatic, low-cost production methods, their price is bound to
become so low that conventional tube and transistor circuits - with
their separate resistors, capacitors, inductances, and complex soldered
connections - will be on the way out, except possibly for highly
Molecular electronic devices will open
up exciting new fields with their combination of high performance,
small size, and low cost. For example, the wrist radio - a la Dick
Tracy - will become common-place. The personal telephone - a tiny
gadget to strap on your wrist or carry in your pocket - will become
possible. With it, you will be able to call anybody in the world
who is similarly equipped.
A flat-screen TV set that hangs
on your wall like a picture will become a reality. Rapid advances
in electroluminescence have already come close to making practical
a screen only a fraction of an inch thick. Molecular electronics
will make it possible to pack the rest of the TV circuitry into
a hollow corner of the frame!
There are endless speculations
possible on the changes molecular electronics will bring - the probable
developments in communications already mentioned are only a few.
But who can say what revolutions in medicine, industry, business,
government, and other phases of human endeavor will come about?
As with most truly revolutionary advances, molecular electronics
will bring about profound changes impossible to predict. We'll be
looking forward to them eagerly, however. For certainly, molecular
electronics, whatever its contributions, will help shape a better
and more exciting world for us all.