Gallium arsenide

Definition

Gallium arsenide (GaAs) is a compound semiconductor made from gallium and arsenic, known for its high electron mobility and direct bandgap, making it an ideal material for high-frequency and optoelectronic applications. This unique combination of properties allows GaAs to perform exceptionally well in devices like diodes, solar cells, and transistors, where efficiency and speed are crucial.

5 Must Know Facts For Your Next Test

1. Gallium arsenide has a direct bandgap of about 1.43 eV, making it suitable for optoelectronic devices such as LEDs and laser diodes.
2. The high electron mobility in GaAs allows for faster signal processing in radio frequency (RF) and microwave applications compared to silicon.
3. GaAs is often used in solar cells for space applications due to its high efficiency and resistance to radiation damage.
4. In p-n junctions formed with gallium arsenide, surface recombination can be a significant factor affecting device performance, especially in high-efficiency applications.
5. Gallium arsenide-based MESFETs are widely used in high-speed applications because of their ability to operate at higher frequencies than silicon-based FETs.

Review Questions

• How does the high electron mobility of gallium arsenide impact its use in high-frequency applications?
  • The high electron mobility of gallium arsenide allows electrons to move quickly through the material when an electric field is applied. This property enables GaAs devices to operate at much higher frequencies than those made from silicon, making them ideal for applications such as RF amplification and microwave communication. As a result, components like MESFETs made from GaAs can achieve better performance in fast-switching circuits.
• Discuss the importance of surface recombination in gallium arsenide solar cells and how it affects their efficiency.
  • Surface recombination is a crucial factor in gallium arsenide solar cells as it can limit the number of charge carriers available for generating electric current. High surface recombination rates can reduce the efficiency of these solar cells by allowing electrons and holes to recombine before contributing to the electrical output. To mitigate this issue, various surface passivation techniques are employed to enhance charge carrier lifetimes and overall cell efficiency.
• Evaluate the advantages of using gallium arsenide over silicon in heterojunction bipolar transistors (HBTs) for modern electronic devices.
  • Gallium arsenide offers several advantages over silicon when used in heterojunction bipolar transistors (HBTs). These include higher electron mobility, which leads to faster switching speeds, and a direct bandgap that enables efficient light emission. Additionally, GaAs HBTs can handle higher frequencies and power levels, making them more suitable for applications like telecommunications and high-speed computing. The combination of these factors contributes to improved performance in modern electronic devices, allowing for smaller and more efficient designs.

Related terms

Bandgap: The energy difference between the top of the valence band and the bottom of the conduction band in a semiconductor, determining its electrical conductivity and optical properties.

Heterojunction: A junction formed between two different semiconductor materials, often used to create devices with improved performance characteristics compared to homojunctions.

Electron mobility: A measure of how quickly electrons can move through a semiconductor when an electric field is applied, directly influencing the speed of electronic devices.