What is the P-N junction, we explain in simple terms

The discovery of P-N transition enabled a revolution in modern electronics. Without it, we would like you have never seen modern computers, phones, TVs and other gadgets so familiar to us. So what is its essence? In this article I'll try to explain it in simple words without boring formulas and arcane phrases. Let's get started.

What is the P-N junction

So, let us look at the principle of work:

As you know, except for conductors and dielectrics there are intermediate materials called semiconductor. And at first it was not clear how they can be used, but after the semiconductor prolegirovat, it becomes quite interesting properties.

The first and most common semiconductor element is silicon, which is a huge amount on our earth (almost 30% of the Earth's crust is made up of this element).

Further there is already a rare metal such as germanium (its proportion of the order of 1.5 x 10-4% in the crust)

Scientists have made the following discovery: if a part of the silicon to add arsenic, he (silicon) is saturated free electrons, as is well known, a material in which the composition of many of the free electrons is a good conductor. Since the electron has a negative charge, so silicon can be considered prolegirovanny N (Negative- -ve) - conductor. Interesting? Further more interesting.

If the same silicon prolegirovat element such as indium, such a conductor becomes a unique property. In the first case we have you appeared free electrons, here in the second embodiment, positive free charges are obtained.

The paradox is that free electrons with a positive charge there. The protons (positively charged particles) are associated with neutrons and are components of an atomic nucleus. That is, they can not carry a positive charge. It turns out he has a charge, and particles carrying it is not there.

Such particles are called "holes" with a positive charge. And the semiconductor material, which included a lot of "holes", called a semiconductor P (Positive - Positive) - type.

By itself, the silicon P - type and N - type is useless, but if the plate of the element is very tight leaning against each friend, just at the point of contact, and there is the notorious P-N junction, which revolutionized modern electronics.

How does the P - N junction

So, if you do not go into the physics of the process, in other words, this transition has unilateral conductivity. Unclear? Let me explain with an example.

Let's take the most ordinary funnel:

If you and I will pour water on the part of the neck, then all the water is quite easy to pass through the funnel, But if we try to pour water through a thin part of the watering can, then only a small part of the water will pass through it.

And a P-N junction, if we are to side with P - plus transition will provide the constant power supply, and N - minus shift, then the current will pass freely through the transition, but if we change the plus and minus some places, the current is not go. just like in the conventional diode.

To test this, let's do a little experiment: take a regular diode, a light bulb on 12 Volt and the power supply and collect under the scheme:

Gathering such a scheme and turn the power supply, we will see with you that the lamp lights. This means that there is no obstacle for the flow of the current, but it is worth to you and me to change the polarity of the power supply and the lamp does not light up.

That is, we are seen clearly that the diode in the operating principle of which is laid, P-N junction, the direct inclusion of conductive, and when there is no reverse.

conclusion

I hope now you become more or less clear what the P-N transition and how it works on the above example with a conventional diode. If you are interested in this topic, subscribe to not miss the latest publications and rate the article Like. Thank you for your attention!