Advancements in Semiconductor Materials
Semiconductors are the backbone of the modern world. They help us build devices that power everything from smart phones to artificial intelligence.
MIT researchers have discovered a material that performs better than silicon in terms of conducting electricity and heat. This discovery could lead to faster, smaller computer chips.
The Indian government has reopened the application process for $10 billion worth of incentives for chip manufacturing. The first applications are expected to be approved soon.
1. Cubic Boron Arsenide
Silicon is the foundation of the electronics industry. It’s used in everything from microchips to solar cells. But despite its immense importance, its performance leaves much to be desired. Scientists recently discovered that an obscure material called cubic boron arsenide (c-BAs) offers impressive electrical and thermal properties, suggesting it could be a superior replacement for silicon.
The researchers found that c-BAs has high mobility for both electrons and holes, the two ways in which charge is carried in a semiconductor. Their experiments, published July 22 in Science, confirmed earlier predictions based on quantum mechanical density functional calculations.
The team also found that c-BAs has excellent thermal conductivity. That means it’s able to transfer heat quickly, which could help prevent overheating and reduce the need for cooling systems in devices. This is an especially critical issue as electronic components become smaller and more densely packed. It’s why silicon carbide, which has three times more thermal conductivity than silicon, is now replacing silicon in power electronics for electric vehicles like Tesla’s.
Germanium was one of the first semiconductor materials used, and it continues to be useful in modern technologies. Its four valence electrons allow it to conduct electricity more efficiently than other elements. It is also used in the wafers that are the basis of most electronic devices, such as cell phones and computers.
Germanium (Ge for short) is a metalloid, meaning it has some properties of both metals and non-metals. It is in group 14 of the periodic table, which includes silicon and tin. Dmitri Mendeleev, who developed the periodic table, predicted that a new element would be found to fill an empty space in this group, and Clemens Winkler discovered germanium in 1886.
Pure germanium is too reactive to occur naturally, but it can be extracted from its compounds. It is used in wide-angle camera lenses and microscope windows, as a light-sensitive material in infrared spectrometers and for making polymerisation catalysts. It is also used in military night vision equipment and advanced fire fighting systems.
3. Gallium Arsenide
Silicon is the material used to make computer chips and solar cells, but scientists and engineers have been on the lookout for a substitute. Gallium arsenide (GaAs) offers advantages over silicon like better heat and moisture resistance, higher electron mobility, and a direct band gap.
It can be used in diodes, bipolar junction transistors and field-effect transistors. GaAs semiconductor devices can be made smaller, faster and generate less noise than other types of electronic components.
Workers working with GaAs can be exposed to vapor, inhalation and ingestion. Exposure to GaAs can cause lung damage, especially in the nose and throat. It has also been shown to cause skin irritation. ATSDR lists gallium arsenide as a hazardous air pollutant (HAP) that may pose a health threat at occupational exposure levels. The Clean Air Act requires major sources to sharply reduce routine emissions of HAPs. Workers should be urged to follow safe handling policies and available engineering controls to protect their health.
Silicon is the most common semiconductor material used in microelectronic devices such as transistors and diodes. Its atomic structure makes it an ideal semiconductor, but it’s often “doped” with impurities such as arsenic, phosphorous and boron to improve its performance and increase its electrical conductivity.
Each silicon atom has four valence electrons in its outer shell that form covalent bonds with its closest neighboring atoms in a regular diamond-like crystal lattice. These covalent bonding electrons make silicon an insulator at absolute zero temperature. But as the temperature rises, these electrons gain enough thermal energy to break free from their atoms and form conduction electrons.
This allows silicon to conduct electricity with a higher speed than metals. It also has a wide band gap, which makes it possible to process ultraviolet light for use in photovoltaics, like solar cells.