Semiconductor Materials

- Overview

Semiconductors are the brains of all electronic devices, from microwaves to cell phones, from drones to cars. They are an essential component in developing technologies critical to economic growth, national security, and global competitiveness. Therefore, countries are competing to win the semiconductor industry race and gain a competitive advantage.

Semiconductor materials range in price and availability, from abundant silicon to expensive rare earth elements (REEs). Solar cells, field-effect transistors, IoT sensors and self-driving car circuits all require semiconductor materials to function. The modern world really owes its existence to semiconductors and the materials used in their manufacture.

As existing semiconductor materials reach their physical limits, new materials are about to replace them. The market for these materials, coupled with new semiconductor applications, is changing manufacturing and material sourcing across industries.

- Semiconductor Materials

Semiconductors are materials which have a conductivity between conductors (generally metals) and nonconductors or insulators (such as most ceramics). Semiconductors can be pure elements, such as silicon (Si) or germanium (Ge), or compounds such as gallium arsenide (GaAs) or cadmium selenide (CdSe). In a process called doping, small amounts of impurities are added to pure semiconductors causing large changes in the conductivity of the material. 

Semiconductor materials are nominally small band gap insulators. The defining property of a semiconductor material is that it can be doped with impurities that alter its electronic properties in a controllable way. Because of their application in the computer and photovoltaic industry -- in devices such as transistors, lasers, and solar cells -- the search for new semiconductor materials and the improvement of existing materials is an important field of study in materials science. 

Most commonly used semiconductor materials are crystalline inorganic solids. These materials are classified according to the periodic table groups of their constituent atoms. Different semiconductor materials differ in their properties.

• Silicon (Si), a very common element, is used as the raw material of semiconductors because of its stable structure. Silicon is found in the form of compounds with Oxygen, Aluminum and Magnesium. As a result, the Silicon element must be extracted from the compound and purified. Silicon used in a semiconductors such as an integrated circuits (IC) requires a single crystal structure of ultra-high-purity “99.999999999%” (the so-called “eleven nines”) and is refined using various processes after extraction. Purification of Silicon consumes large amounts of power.
• Germanium (Ge), an important semiconductor, is mainly used in transistors and integrated circuits. They are often made from germanium to which small amounts of arsenic, gallium, or other metals. Germanium forms many compounds. Germanium oxide is added to glass to increase the index of refraction; such glass is used in wide-angle lenses and in infrared devices. Numerous alloys containing germanium have been prepared. High purity germanium single crystal detectors can precisely identify radiation sources (e.g. for airport security).
• Silicon (Si) has long held its place as the key material in semiconductors. However, Gallium Arsenide (GaAs), along with other compounds like gallium nitride and silicon carbide, are now sharing the stage. Gallium Arsenide (GaAs) is a compound built from the elements Gallium and Arsenic. It is often referred to as a III-V compound because gallium and arsenic are in the III group and V group of the periodic table, respectively. The use of GaAs is not a new technology. In fact, DARPA has been funding research into the technology since the 1970s. While silicon-based technology has been the backbone substance of the microelectronics revolution, GaAs circuitry operates at the higher frequencies and signal amplification powers that have made practical a world connected by palm-sized cell phones. Gallium arsenide led to the miniaturization of GPS receivers in the 1980s. This made the laser-guided, precision munitions that entered US arsenals during that time period possible.
• Cadmium selenide (CdSe) is an inorganic compound. It is a black to red-black solid that is classified as a II-VI semiconductor of the n-type. Much of the current research on this salt is focused on its nanoparticles. CdSe is a tetrahedral semiconductor with wurtzite structure in the hexagonal modification. CdSe is an optically uniaxial semiconductor with two components of the dielectric function. Measurements of the reflectivity spectra of CdSe crystals with polarized light show strong differences for the electric vector parallel and perpendicular to the hexagonal axis.

- Generations of Semiconductor Materials

There are many different types of semiconductor material. These different types of semiconductor have slightly different properties and lend themselves to different applications in various forms of semiconductor devices.

Some may be applicable for standard signal applications, others for high frequency amplifiers, while other types may be applicable for power applications and harsh environments or others for light emitting applications. All these different applications tend to utilise different types of semiconductor materials.

• The first-generation semiconductor materials are silicon (Si), indirect band gap, narrow band gap.
• The second-generation semiconductor materials are gallium arsenide (GaAs), direct band gap, narrow band gap.
• Third-generation semiconductor materials are currently relatively mature Silicon carbide (SiC), gallium nitride (GaN), etc., wide band gap, full component direct band gap.

In the 1970s, “silicon” ignited a tech-revolution, and changed the world. But after decades of pushing the envelope, silicon has reached the outer-limits of its capabilities. In short, silicon can no longer support the incredible technologies that are becoming essential to modern society. The end of silicon is upon us.
 
A revolutionary new metal, GA-31 (Gallium-31), has emerged… MIT calls it the “new silicon”… The U.S. Government calls GA-31 a “smart metal… Because of its one-of-a-kind molecular structure, GA-31 is able to perform feats of scientific wizardry that put silicon to shame. As a result, every major company on the planet - from Google, to Apple, to Intel, to Facebook and beyond - are stampeding out of silicon…and into GA-31. 
   
And there are several reasons why:

• First, because of GA-31’s unique molecular structure, it has an astounding ability to conduct electrons. In short, they fly around at up to 1,300 miles per second. As a result, this metal offers astounding speed and power, far beyond the abilities of silicon. In fact, this GA-31 is up to 100 times faster than silicon… Not only does this allow Smart Phones and Laptops to perform with dizzying speed and prowess…But it also allows for modern-day technologies that silicon simply can’t support… We are talking about Lasers, 3D-Sensors, Virtual Reality, Facial Recognition, Self-driving Cars, Smart Homes, and more. 

• As you may know, silicon degrades at high temperatures. That’s a big problem because today’s smartphones contain billions of transistors all operating simultaneously. That generates tremendous heat. Silicon can’t handle it. But when you “dope” GA-31 with a second ingredient, it can withstand extreme heat, up to 4,532 degrees Fahrenheit! This makes it ideal for cutting-edge applications, including weather satellites, solar panels, radars, and military defense systems. Add it all up, and GA-31 is essential to modern society.

 
Again, every major company on the planet – including Intel, Apple, and Google—are transitioning out of silicon and into GA-31!