Video Transcript
Which of the following materials is a semiconductor that is often used to make
diodes? (A) Copper, (B) neon, (C) lithium, (D) silicon, (E) iridium.
In this question, we’re asked to pick out the semiconductor that is often used to
make diodes from the five materials given. We will look at each of these options. But first let’s recall what a diode is and why we use semiconductors to create
them.
A diode is an electronic component that is used in circuits to limit the direction of
current. They have many uses and can be found in many different electronics. Diodes work by only allowing current through them in one direction and blocking
current from the other direction. They are represented by these symbols on a current diagram, and the symbol will point
in the direction of allowed direction of current.
We want a diode to act like a switch that flips with potential difference. When it is positive, there is very little resistance, and when it is negative, there
is a lot of resistance. Semiconductors make perfect materials to build diodes out of. So let’s look through our options and see which one is a semiconductor. Remember that semiconductors have a conductivity in between that of insulators and
conductors. They also typically have four electrons in their outer shells.
Let’s start with the first option, copper. Copper is a highly conductive metal that is commonly used as a wire because of its
high conductivity. Therefore, it is not a semiconductor and not a good material to make diodes out
of.
The next option, neon, is a noble gas. Recall that noble gases have their entire outer shells full and are not reactive. This means that neon is not the material we are looking for here.
Now, the third option, lithium, is a metal that is highly reactive and
conductive. It also only has one valence electron, which leads to its high reactivity, and is not
a good material to craft diodes with.
But the fourth option, silicon, does have four valence electrons and is considered a
great semiconductor to make electronic parts with. This could be the correct answer, but let’s check the last option just in case.
Iridium is a metal in the platinum group and is stable and very conductive with seven
valence electrons. This means it is not a great option to choose to make diodes with.
This means that silicon is the only semiconductor on the list. Therefore, the fourth option, silicon, is the correct answer.
