When I first began building my computer, I learned that most computer parts only require about three different voltages, but wall sockets in the US produce 110 volts and other countries use 220 volts. That got me wondering, wouldn’t the 110 volts travel all throughout the computer? How do computer parts reduce the voltage? After getting my computer running, I researched my question for the answer: transistors. It didn’t really gave me a full understanding of how, so I decided to do more research.
If cells are the building blocks of life, transistors are the building blocks of the digital revolution. Without transistors, the technological wonders you use every day — cell phones, computers, cars — would be vastly different, if they existed at all.
– Nathan Chandler at HowStuffWorks, (Chandler, n.d., p. 1)
So the guys at HowStuffWorks gave a brief overview of how transistors work. Transistors are somewhat like water faucets. In addition to starting and stopping the current, they can control how strong the current is, allowing the resulting voltage to be bigger or smaller than the original. All this is thanks a series of semiconductors, once made out of germanium is now mostly produced with silicon. Semiconductors are materials that can conduct electricity, but not very well. Naturally, Si and Ge are very weak semiconductors, conducting almost no electricity at all, but through a process called doping, the conductive properties can be changed.
Doping is the process of adding small amounts of impurities into, in this case, silicon or germanium crystal lattice. Both Ge and Si have 4 valence, the impurities usually come from either group 3 or group 5 elements, depending on the type of semiconductor desired. Having 3 valence electrons, elements such as boron and aluminum can be added to Si, creating a substance where the added impurity is missing an electron. This is called a P-type due to its positive charge from the missing electrons. Conversely, phosphorus or arsenic, elements with 5 valence electrons can be added to create N-type semiconductors due to its additional electrons giving a negative charge. A nice diagram is can be seen here in Hyperphysics.
Now equipped with both types of semiconductors, you can create a transistor by placing a series of either P-N-P or N-P-N. When applying an electrical current in the middle, “electrons will move from the N-type side to the P-type side.” Depending on the initial strength of the current and how impure the semiconductors are, the transistor will either amplify or decrease the current.
All this got me thinking on another question of mine. What other uses are there for semiconductors? The simplest use of semiconductors is diode. A diode consists of one P-type and N-type semiconductors. When put together, an electrical current can flow through from the P-type region to N-type region, but not the other way. This is because electrons can only flow from positive to negative, but not the other way around, as the N-type region will repel the moving electrons.
These can be made into Light Emitting Diodes, or LED’s, that emit a multitude of colors. Multiple semiconductors can be combined to create Random Access Memory (RAM) to increase your computer’s speed or Microprocessors for calculators and other electronic devices.
So to put it in perspective, just as cells build living things, transistors, according to Nathan Chandler, are the building blocks of all electronics. But seeing as semiconductors build transistors, I believe that these special compounds are the true cells in electronics. Although semiconductors have existed in electronics for quite some time, new uses and circuitry of electronics is being discovered every day.
Chandler, Nathan. “HowStuffWorks “How Transistors Work”.” HowStuffWorks. N.p., n.d. Web. 13 Jan. 2013. <http://electronics.howstuffworks.com/transistor.htm>.
“Semiconductor Device.” Wikipedia. N.p., n.d. Web. 13 Jan. 2013. <http://en.wikipedia.org/wiki/Semiconductor_device>.
“The Doping of Semiconductors.” Hyperphysics., n.d. Web. 13 Jan. 2013. <hyperphysics.phy-astr.gsu.edu/hbase/solids/dope.html>.