Miniature radios, televisions, headphones - they are very much indebted to their little electronic titans called transistors. What is behind these electronic wonders? The ideas have a lot to do with a branch of physics called quantum mechanics, which is about very small objects, such as atoms and electrons.

What do transistors do? What are its benefits? How they are created

In principle, a transistor does the same job as a vacuum valve. Many of its applications focus on its function as an amplifier. In other words, the transistor amplifies the signals received, for example with radio and TV antennas.

It can be believed that this amplifier takes a small amount of an electrical signal on one side of the transistor, copies it and produces a large amount of wiring diagram on the other side. The transistor used as an amplifier takes an electrical image as current and produces perhaps twenty times the input current with the same wiring diagram.

BENEFITS

You may be wondering if transistors basically do the same thing as a tube, why bother? Because the transistor has advantages over its ancestor, the vacuum valve.

The first advantage is the small size of the transistor. That's about one-hundredth of the size of a similar performance vacuum valve; In other words, a tube can be the size of a human thumb, but a transistor is the size of a pea. Thanks to transistors, it is possible to miniature all types of electronic devices.

Another advantage of these small electronic titans is that they can run on much less current than pipes. This is because transistors do not have a filament or a heater. For a tube to work, it must have a heater called a filament (like a burner in a much smaller electrical area) to "boil" electrons from the cathode or electron-emitting area of ​​the tube. pipe. The transistor does not need such a heating element. And since the transistor barely produces heat, it does not heat up. When a pipe overheats, it consumes energy.

Other advantages are: the transistor, which does not need heating as valves, starts working immediately. The transistor is also more durable because it does not have thin wires like dangling tubes. As a result, the transistor has higher reliability. Some people estimate that a transistor that works all day and all night, every day of the year, would last eight to ten years. There are actually few reasons why these little electronic titans wear out; but shocks, sudden changes in temperature and humidity affect them.

Due to its many advantages, the communication satellite is one of the things that transistors have made possible. On July 3, 1962, the Telstar communications satellite was used to broadcast live television from the United States to Europe. Telstar received signals from a ground station in the United States, amplified these signals and then transmitted them so that they could be detected at another remote ground station. Because transistors run on very little current, batteries powered by sunlight can be used to supply power. The Telstar satellite uses a vacuum tube, 1,064 transistors and other semiconductor devices. The communications satellites launched by Telstar use all transistors. But what are transistors made of?

MADE OF SEMICONDUCTORS MATERIAL

Materials that conduct electricity very simply are called conductors. Silver, aluminum and copper, for example, are conductors. Why is a certain material a good leader? This is due to the large number of free electrons in the material. What exactly do we mean by "free" electrons? Well, electrons are free in these materials because they can easily move from one atom, including the conductor, to another.

Unlike materials that are good electrical conductors, some materials are called insulators. These materials do not have free electrons. Consequently, electricity will not easily pass through them. Of course, these materials are used in household appliances to avoid impact. That is why we have rubber-lined electrical sockets and plastic light switches.

There is still a third class of materials: a type of solids called semiconductors. Materials in this class do not conduct electricity very well or are good insulators. Therefore, these materials are called semiconductors. Germanium (discovered by a German chemist and named for Germany) and silicon are the best-known semiconductor materials.

Now, why is the third class of materials not suitable for use as a conductor or an insulator? The reason they are just good conductors is that they don't have free electrons. They are also not good insulators, because it doesn't take a lot of energy to produce free electrons. In fact, the number of free electrons increases about a million times when the temperature rises from 0 ° F to about 350 ° F.

Transistors start with a pure crystalline semiconductor material, and since that material is in the solid state of matter, as opposed to liquid and gaseous states, transistors are considered "solid state" devices.

IMPURITIES MUST BE ADDED

Interestingly, semiconductor material cannot be used with great force in its pure state; but when the right amount of impurity is added it can really work.

But why do we have to add impurities? Because a slight trace of certain impurities produces few free electrons or no electrons. Therefore, some impurities do not produce free electrons, but do remove electrons from some atoms in the semiconductor. The result? Lack of electrons in an atom. This is called a hole. However, the advantage of a "hole" is that it can move from one atom to another. And a flow from these "holes", moving from one atom to another, forms an electric current. The "hole" becomes a carrier of positive electricity, which is the opposite of the negatively charged electron.

The semiconductor material that has free electrons is called n-type (due to the negative charge). When the material has "holes" or electron deficits, it is called p-type (due to the positive charge).

To illustrate: if arsenic dissolves in very pure molten silicon or germanium, then there are a large number of electrons that can be considered nearly free electrons. The result is an n-type material because the arsenic atom has five outer electrons per atom, while germanium has only four, so there is an abundance of electrons. These electrons are easily excited to become free electrons.

What happens if boron or aluminum is added to the semiconductor material? Well, these two elements have only three outer electrons. So there is a shortage of electrons compared to germanium; therefore, there is a "hole". The result is a p-type material.

MADE OF LAYERS OF MATERIAL

Therefore, the transistor is made of a layer of p-type material sandwiched between two types of nodes. This is called an n-p-n transistor. Or a transistor may consist of a layer of n-type material between two types of sheets. This is called a p-n-p transistor.

The junctions where these materials meet are where the amplifying action occurs. Valves can be considered that make the current flow freely or not, depending on how the electrical potential or voltage is placed between these two junctions.

MICROMINIATURIZATION

Although the transistor is small and consumes little power compared to the valve, new developments have made electronic packages smaller than possible, even with transistors. They are called integrated circuits or simply integrated circuits.

In this new development, the transistors along with other elements of the circuit are assembled in a series of layers. These little packages are complete circuits rather than a single component (like a transistor) in a circuit. Integrated circuits allow micro-miniaturization.

The annual World Scientific Year of Science Book states: “Today's integrated circuits are one-tenth of an inch square and a few thousandths of an inch. Like transistors, they use little electricity in the form of heat and therefore require relatively little cooling. . . . A TV made entirely of integrated circuits, with the exception of the CRT and the speaker, would fit in a small matchbox. "

To illustrate the difference between complete circuits and individual components of a circuit, consider a box the size of a half gallon milk container. Now a circuit containing perhaps one hundred conventional parts can be placed in this box. But with integrated circuits, how many parts can be placed in the same space? About one billion (trillions).

So the new development is really amazing. Human advances in the art of miniaturization are largely due to transistors, these small electronic titans. However, the microminiaturation itself is not new. The creator of man micro-miniaturized the human brain. He designed it so that about one hundred billion (one hundred billion million) coins could be used in that space.