Gallium arsenide can be used to make transistors, much like the more common semiconductor silicon. GaAs based circuits are usually capable of much greater speeds than silicon. Seymour Cray pushed for widespread adoption of the substance in computer chips and used it heavily in the creation of his supercomputers. GaAs is also used in space hardened applications because it is better at withstanding the large amount of radiation in space. There are two major drawbacks to gallium arsenide though. First, it is extremely expensive to use GaAs rather than silicon. Second, due to the arsenic that it contains, it is poisonous and dangerous to work with and to manufacture.

Gallium arsenide (GaAs) is the most important non-silicon semiconductor. GaAs has many electrical properties superior to those of silicon. However, GaAs suffers from a few drawbacks that ensure that silicon (Si) will maintain its dominance in the future.

Useful properties of gallium arsenide

Unfortunate properties of gallium arsenide

  • No high-quality insulators (counterparts to silicon dioxide) grow on GaAs. The insulator/GaAs interfaces have high levels of defects called "traps" that make GaAs MOSFET's impossible. This is probably the main reason that GaAs will never supplant Si as the semiconductor-of-choice for integrated circuits. GaAs transistors are usually either MESFET's or HEMT's. These transistors have some advantages over MOSFET's but their disadvantages outweigh the advantages.
  • GaAs is extremely brittle. For this reason, GaAs wafers are typically smaller than three inches in diameter, as opposed to silicon wafers, which commonly have diameters of eight or more inches. Since the area on a wafer is proportional to the square of its diameter, Si has a huge cost advantage over GaAs.
  • The hole mobility in GaAs is 15-20 times smaller than the electron mobility, which makes CMOS-like circuits unattractive.

Some material constants of gallium arsenide

I used these two references:

  • Digital Integrated Circuits by Jan Rabaey
  • CRC Handbook of Electromagnetic Materials by Perambur Neelakanta

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