Silicon is an element with an atomic number 14 which is found in abundance in the earth in the form of a hard solid grey state. It is denoted by symbol as ‘Si’. Many students may have a doubt regarding the conductivity of Silicon. In this article, you’ll get to know about the conductivity in silicon.
So, does Silicon conducts electricity? Yes, Silicon conducts electricity as it is a semiconductor. The conductivity of Silicon gets better with increasing the temperature of it. This is because of the unique property of semiconductors whereas, in the case of metals, the conductance of electricity decreases with an increase in temperature.
Silicon is used in many electronics appliances as it is an element that consists of unique properties. One such property of silicon is that it is a semiconductor. Semiconductors conduct electricity under some condition whereas it also acts as an insulator under other conditions.
Apart from being a semiconductor, it is present in abundance in the earth’s crust which is also a reason to use for making electronic devices. The appliances such as processor chips, solar panels, diodes, etc have silicon metals present in them. Due to its abundance, it is affordable too in comparison to other semiconductors.
It is also important to know what are semiconductors? So, firstly we should know about semiconductors for more clarity.
What is a semiconductor?
Semiconductors are the material that contains the properties of conductors and insulators both. They conduct electricity under some conditions. Basically, the temperature plays an important role in the conductance of electricity in semiconductors.
At normal room temperature, the semiconductor conducts electricity because at this temperature the free electrons are available to flow across it which in return produces the electric current.
At 0 degrees or close to absolute temperature, there are almost no free electrons to flow which makes it an insulator at this temperature.
Unlike metals, the conductance of electricity of silicon gets better with the increase in its temperature. The conductivity of metals gets worse on heating. This occurs because on heating the metal, the molecular vibrations increases which causes obstruction to the free electrons to move that helps in conducting electricity.
In semiconductors, on increasing temperature, the electrons around the semiconductor atom involved in the covalent bond can easily break away and move freely across the lattice.
The Silicon has its great use in renewable energy resource that converts solar energy into electrical energy. This is because the Silicon being a semiconductor gets enough energy from the sunlight and the electrons get threshold energy to get out of bond and flow across the lattice. Due to this, the electrons take participate in the conductance of electricity in solar panels.
In a semiconductor, when an electron gains energy required to take part in electrical conductance, it is said to be in the high state. When the electron is bound to its atom, then it is said to be in the low state.
Therefore, in a semiconductor, the state of the electron is either a low state or a high state. And the gap between these two levels of energy is known as the bandgap. Basically, the bandgap is the minimum energy required by an electron in a low state to attain a high state.
The electron that breaks out the bond leaves behind a hole. So, the factors that impact the conductivity in a semiconductor are as follows:
- Number of free carriers
- Generation and recombination of carriers
Silicon in Solar Panel
If we talk about the solar panels, the electrical energy produced by them contributes an appreciable amount to renewable energy. About 90% of the solar cell is based on Silicon. They came into use around the 1950s.
The silicon in a solar cell has impurities added to it to enhance conductivity. Here, impurities are referred to as the other atoms that are forcefully added in the silicon. This is done to improve the capability of silicon to capture the sunlight and further convert it into electricity.
We can understand it by taking an example. The Arsenic atom has one electron more than silicon in the valence shell. On adding arsenic atom in silicon, an electron-rich layer is maintained because of extra electrons.
Similarly, gallium has one electron lesser than silicon in its valence shell. On its addition, due to the deficiency of electrons, the electron-deficient layer is created. And these layers are organized in such a way that they lie next to one another. And when sunlight falls over them, then electrons flow strongly which in return produces an electric field.
Silicon has a bandgap of 1.1 EV at 273 Kelvin which is reasonably good to achieve with the sunlight.
These electrons leave behind holes while flowing which gets filled with preceding electrons flowing across the lattice. The holes and electrons are known as carriers in the working of the solar cells. In this way, electricity is produced by solar energy.
When solar cells were used commercially in the 1950s, its efficiency was limited only up to 6 percent. But over the decades, there are a lot of improvements done in the Silicon for the efficient working of the solar cells.
One such improvement is adding impurities in silicon to increase the capability of capturing sunlight. Another improvement in solar panels came with black silicon.
Black Silicon Solar Cell
Black Silicon is made black by some process named as etching. The advantages of black silicon used in a solar panel are that the sunlight is absorbed throughout the day.
Crystalline silicon captures sunlight optimally during the peak hours as photon particle falls perpendicularly on the surface of silicon, but, black silicon has a greater capacity of sunlight absorption at all angles of photons striking on black silicon.
Black silicon is done by an etching process which is a single-sided process and a smooth surface on another side can be used for some productive layout. The other benefit of black silicon is also that it does not require anti-reflecting coating.
Solar panels are usually expensive because they require a proper installation which is fairly high.
Conclusion: Does Silicon Conduct Electricity?
Silicon is a semiconductor and it can act as a conductor and insulator both under different conditions. At zero degree temperature, it acts as an insulator because no free electrons are present that can move across the lattice to conduct electricity.
And at room temperature or above, it acts as a conductor due to the presence of free electrons. Unlike metals, the conductance of electricity of silicon increases with the increase in temperature.