Natural semiconductors: Difference between revisions
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Semiconductors have become critical to the world in which we live, and yet the knowledge about what they are and what they do is quite limited, even with people trained in electronics. They are materials where the electrical current | Semiconductors have become critical to the world in which we live, and yet the knowledge about what they are and what they do is quite limited, even with people trained in electronics. They are materials where the electrical current they conduct is non linearly dependent on the voltage level. The simplest semiconductor component is the diode, commonly understood to only pass current in one direction across it's two terminals. It actually does two things: | ||
# | # It won't start conducting until a certain voltage has been reached. | ||
# | # This threshold is different depending on which way round it's been connected (it has asymmetry). | ||
The | The forward threshold voltage is much (much) lower than the reverse. With silicon diodes this is about 0.7 volts one way and 100 volts in the other. Different semiconducting materials are used to obtain different results, germanium diodes have a lower forward threshold of 0.3 volts. | ||
The theory of how electrons move through crystal lattices explaining why this happens was only understood around 30 years after they entered common use. | |||
= Natural vs factory grown semiconductors = | = Natural vs factory grown semiconductors = | ||
The silicon used in our technology may be grown in a factory, but the raw material still has to be mined. Mostly this comes from high purity quartz | The silicon used in our technology may be grown in a factory, but the raw material still has to be mined. Mostly this comes from high purity quartz extracted from a handful of regions of China. This material is purified further and grown into mono-crystalline blobs of silicon metal. | ||
Natural semiconductors, such as [[pyrite]] or [[galena]] grew millions of years ago | Natural semiconductors, such as [[pyrite]] or [[galena]] grew millions of years ago, approximately 270, in the case of Cornish mineralisation. Material from different locations (sometimes only metres apart) have different patterns of crystallisation due to slightly different temperatures or impurities. These changes can also affect their semiconductor behaviour. | ||
[[List of minerals tested]] | [[List of minerals tested]] | ||
Revision as of 17:49, 31 December 2025
Semiconductors have become critical to the world in which we live, and yet the knowledge about what they are and what they do is quite limited, even with people trained in electronics. They are materials where the electrical current they conduct is non linearly dependent on the voltage level. The simplest semiconductor component is the diode, commonly understood to only pass current in one direction across it's two terminals. It actually does two things:
- It won't start conducting until a certain voltage has been reached.
- This threshold is different depending on which way round it's been connected (it has asymmetry).
The forward threshold voltage is much (much) lower than the reverse. With silicon diodes this is about 0.7 volts one way and 100 volts in the other. Different semiconducting materials are used to obtain different results, germanium diodes have a lower forward threshold of 0.3 volts.
The theory of how electrons move through crystal lattices explaining why this happens was only understood around 30 years after they entered common use.
Natural vs factory grown semiconductors
The silicon used in our technology may be grown in a factory, but the raw material still has to be mined. Mostly this comes from high purity quartz extracted from a handful of regions of China. This material is purified further and grown into mono-crystalline blobs of silicon metal.
Natural semiconductors, such as pyrite or galena grew millions of years ago, approximately 270, in the case of Cornish mineralisation. Material from different locations (sometimes only metres apart) have different patterns of crystallisation due to slightly different temperatures or impurities. These changes can also affect their semiconductor behaviour.