lot, but if progress was to be made, these requirements had to be met. A serious study of semiconductor
materials began in the early 1940s and has continued since.
In June 1948, a significant breakthrough took place in semiconductor development. This was the
discovery of POINT-CONTACT TRANSISTOR. Here at last was a semiconductor that could amplify.
This discovery brought the semiconductor back into competition with the electron tube. A year later,
JUNCTION DIODES and TRANSISTORS were developed. The junction transistor was found superior to
the point-contact type in many respects. By comparison, the junction transistor was more reliable,
generated less noise, and had higher power-handling ability than its point-contact brother. The junction
transistor became a rival of the electron tube in many uses previously uncontested.
Semiconductor diodes were not to be slighted. The initial work of Dr. Carl Zener led to the
development of ZENER DIODE, which is frequently used today to regulate power supply voltages at
precise levels. Considerably more interest in the solid-state diode was generated when Dr. Leo Esaki, a
Japanese scientist, fabricated a diode that could amplify. The device, named the TUNNEL DIODE, has
amazing gain and fast switching capabilities. Although it is used in the conventional amplifying and
oscillating circuits, its primary use is in computer logic circuits.
Another breakthrough came in the late 1950s when it was discovered that semiconductor materials
could be combined and treated so that they functioned as an entire circuit or subassembly rather than as a
circuit component. Many names have been given to this solid-circuit concept, such as INTEGRATED
CIRCUITS, MICROELECTRONICS, and MICROCIRCUITRY.
So as we see, in looking back, that the semiconductor is not something new, but it has come a long
way in a short time.
Q1. What is a solid-state device?
Q2. Define the term negative temperature coefficient.
In the previous paragraphs, we mentioned just a few of the many different applications of
semiconductor devices. The use of these devices has become so widespread that it would be impossible to
list all their different applications. Instead, a broad coverage of their specific application is presented.
Semiconductor devices are all around us. They can be found in just about every commercial product
we touch, from the family car to the pocket calculator. Semiconductor devices are contained in television
sets, portable radios, stereo equipment, and much more.
Science and industry also rely heavily on semiconductor devices. Research laboratories use these
devices in all sorts of electronic instruments to perform tests, measurements, and numerous other
experimental tasks. Industrial control systems (such as those used to manufacture automobiles) and
automatic telephone exchanges also use semiconductors. Even today heavy-duty versions of the solid-
state rectifier diode are being use to convert large amounts of power for electric railroads. Of the many
different applications for solid-state devices, space systems, computers, and data processing equipment
are some of the largest consumers.
The various types of modem military equipment are literally loaded with semiconductor devices.
Many radars, communication, and airborne equipment are transistorized. Data display systems, data
processing units, computers, and aircraft guidance-control assemblies are also good examples of