Everything You Ever Wanted To Know About Semiconductors
You’ve undoubtedly heard of semiconductors. They really are everywhere. But while most people have heard of semiconductors, very few people know much about them.
We intend on changing that.
Consider this your introduction to the world of semiconductors. By the end of this article, you’ll be able to discuss the subject confidently, which may not win you many dates but will certainly earn you the respect of electrical engineers.
What Is A Semiconductor?
A semiconductor is a physical substance designed to manage and control the flow of current in electronic devices and equipment. It either doesn’t allow a freely flowing electric current or repels the current completely.
A semiconductor sits between a conductor and an insulator and is commonly used in the development of electronic chips, computing components, and devices. It’s generally created using silicon, germanium or other pure elements.
Semiconductors are created by adding impurities to the element. The conductance or inductance of the element depends on the type and intensity of the added impurities.
There are two basic types of semiconductors. An N-type semiconductor is used when its conductance is higher, or there is a large number of free electrons. A P-type semiconductor is used when its inductance is higher, and there are less free electrons.
Conventional devices and components built by using a semiconductor include computer memory, integrated circuits, diodes, and transistors.
If you want an in-depth look at how semiconductors are made, here’s a helpful video:
Elements Used To Create Semiconductors
Let’s get a closer look at two elements that are used to create most semiconductors.
Silicon is the second most abundant element on earth, making up almost over 25% of the earth’s crust by weight. Although not found as a free element in nature, it occurs as oxide and silicates including agate, amethyst, citrine, jasper, flint, opal, quartz, and sand. Silicon metal is derived from reactions between silicon dioxide and carbon materials like coal and wood chips.
Regarding the significant producers of silicon for wafers, there are many suppliers in the US and around the world, primarily in California, Oregon, Florida, Asia-Pacific, China, and Europe. It is believed that China is the largest producer of silicon, followed by the United States.
Germanium is a chemical element that is similar in appearance to silicon, and not found as a free element in nature because of its reactivity factor. Available in the earth’s crust, it is mined from sphalerite zinc ores and can also be extracted from fly ash coal and copper ores.
Germanium is less useful than silicon due to its thermal sensitivity and cost, but it is still alloyed with silicon for use in some high-speed devices. IBM is a primary producer of these devices. The leader in germanium production in China, with the other major producers including the USA, Canada, Russia, and Belgium.
Finding New Semiconductors
Because semiconductors are such a valuable item, companies are constantly searching for new, better ways to make them.
The search for new semiconductors begins on the periodic table of the elements. In the IVA column, each element forms bonds by sharing four of its electrons with four neighbors. The strongest of the group is carbon, used for building diamonds. Diamonds make good insulators because carbon holds on to these electrons tightly, but generally, a diamond would burn before you could force an electrical current through it.
Tin and lead are much more metallic. They hold their bonding electrons so loosely that when even a small amount of energy is applied, the electrons are free to break their bonds and move through the material.
Silicon and germanium are somewhere in between and are considered semiconductors. However, because of the way they’re structured, both are inefficient at exchanging electricity with light.
To find materials that work with light, you have to look to either side of the IVA column of the periodic table. Combining elements from groups IIIA and VA results in materials with semiconducting properties. These materials, including gallium arsenide, are used to create lasers, LED lights, and photodetectors. They can do what silicon can’t.
In addition to IIIA-VA materials, IIA-VIA materials are also in use. These include combinations of zinc, cadmium, mercury, and tellurium.
China’s Plan To Boost Semiconductor Productivity
The production of semiconductors is a big business that can bring in a lot of money. Semiconductor production seems to be a top priority for officials in China. Citing unnamed sources, The Wall Street Journal has reported that the government-backed China Integrated Circuit Industry Investment Fund would allocate the funding to improving China’s ability to design and manufacture advanced processors and GPUs.
The size of the fund, which had previously been reported to be valued at between $19 billion and $32 billion, may have been increased as the result of boiling trade tensions between China and the U.S.
State-backed funding of China’s semiconductor industry has emerged as a focus of the trade tensions that have bubbled up between the two nations, with each country ready to impose tariffs on billions of dollars worth of products. The U.S. claims that China’s government support for its semiconductor industry is anti-competitive.
Why would this plan improve China’s ability to design and manufacture advanced microprocessors?
The Chinese government has stepped up efforts to create a domestic semiconductor industry to help supply its massive electronics market, signaling its intention to spend $161 billion over ten years to further that effort. China currently imports more than $100 billion worth of semiconductors every year.
The latest China Integrated Circuit Industry Investment Fund will follow a similar fund launched in 2014 that raised about $22 billion, according to the report by Wall Street Journal.
The recent trade disputes with the U.S. have created increased urgency for China to bolster its domestic semiconductor industry. The U.S. recently slapped an export ban on Chinese telecommunications provider ZTE, preventing U.S. suppliers of semiconductors and other components from selling devices to ZTE, a significant customer of Qualcomm and other U.S. chip vendors.
China Offers To Buy More US Semiconductors
Because of the recent trade disputes, China has offered to buy more semiconductors from the United States by diverting some purchases from South Korea and Taiwan, to help cut China’s trade surplus with the U.S.
To avert a looming trade war with the U.S., Chinese officials are also rushing to finalize new regulations that will allow foreign financial groups to take majority stakes in its securities firms, Financial Times said, citing people briefed on the discussions.
Even More Tension Between China And The US
A former Huawei employee has accused the company of trying to steal intellectual property to help China achieve technological dominance over the US.
Huawei and its FutureWei unit sued Huang and his start-up CNEX Labs last December, accusing Huang of making off with sensitive trade secrets related to semiconductor technology that uses integrated circuits as memory to store data.
Huang, in a response filed on Tuesday, said Huawei got it backward. He claims he was hired so the Chinese company could take control of his inventions for Solid State Disk Non-Volatile Memory and then, after he left, sought to obtain proprietary information from his new company.
This lawsuit goes beyond semiconductor technology, however. While it will be up to a federal court in eastern Texas to determine who owns the technology, Huang’s filing seeks to capitalize on criticisms that Huawei isn’t playing fair.
The filing includes corporate espionage allegations filed by other American companies and a congressional report that said the use of Huawei equipment “could undermine core US national-security interests.”
“Huawei and FutureWei have served as critical participants in a corporate espionage campaign orchestrated to steal intellectual property from American technology companies, like CNEX, in hopes of surpassing the United States as the world’s predominant technological superpower by 2025,” Huang said in his filing.
New Metal-Air Transistors
Now as we move away from the tensions between China and the US, let’s talk about a technology that could end up replacing semiconductors all together.
It is widely predicted that the doubling of silicon transistors per unit area every two years will come to an end around 2025 as the technology reaches its physical limits. However, researchers at RMIT University in Melbourne, Australia, believe a metal-based field emission air channel transistor (ACT) they have developed could maintain transistor doubling for another two decades.
The ACT device eliminates the need for semiconductors. Instead, it uses two in-plane symmetric metal electrodes (source and drain) separated by an air gap of fewer than 35 nanometers, and a bottom metal gate to tune the field emission. The nanoscale air gap is less than the mean free path of electrons in the air; hence electrons can travel through the air under room temperature without scattering.
Unlike conventional transistors that have to sit in silicon bulk, their device is a bottom-to-top fabrication approach starting with a substrate. This enables them to build fully 3D transistor networks if they can define optimum air gaps. This essentially means they can stop pursuing miniaturization, and instead focus on compact 3D architecture, allowing more transistors per unit volume.
Using metal and air in place of semiconductors for the main components of the transistor has many other advantages, as well. Fabrication becomes essentially a single-step process of laying down the emitter and collector and defining the air gap. Although standard silicon fabrication processes are employed in producing ACTs, the number of processing steps are far fewer, given that doping, thermal processing, oxidation, and silicide formation are unnecessary. Consequently, production costs should be cut significantly.
Replacing silicon with metal means these ACT devices can be fabricated on any dielectric surface, provided the underlying substrate allows useful modulation of emission current from source to drain with a bottom-gate field. Machines can be built on an ultrathin glass, plastics, and elastomers so that they could be used in flexible and wearable technologies.
Technology Is Always Changing
The world of semiconductors is always changing. Whether it’s because of tensions between two countries, or new innovations trying to replace semiconductors all together, in 5-6 years the technology will likely be completely different.
The good news is that, for now, you know enough to talk intelligently about semiconductors. So go out there and impress people. Or at least make yourself look smart.