What Is A Compound Semiconductor?
A compound semiconductor is a material with electrical conductivity that falls between conductors and insulators. Unlike the well-known silicon in most computer chips, a compound semiconductor is made of a crystal lattice structure containing atoms from two or more elements.
These are created by combining elements from Groups III and V of the periodic table (like gallium arsenide, GaAs) or Groups II and VI (like cadmium telluride, CdTe). The process creates a wider variety of materials with unique properties than what single elements can offer.
What Are Some Common Compound Semiconductors?
Here are some of the most common compound semiconductors and their applications:
Gallium Arsenide (GaAs)
Gallium arsenide (GaAs) was one of the first widely used compound semiconductors. It has several important properties that make it useful for several applications. One of the key properties of GaAs is its high electron mobility, which allows electrons to move through the material very easily. The high electron mobility makes GaAs ideal for applications that require high-speed operation, such as microwave circuits. The compound is also used in some transistors and high-efficiency solar cells.
Gallium Nitride (GaN)
Gallium nitride (GaN) is known for its wide bandgap, which is the energy difference between the valence band (where electrons reside in their most stable state) and the conduction band (where electrons can move freely conducting electricity). A wider bandgap allows GaN to handle higher voltages and operate at higher temperatures without breaking down, making it ideal for high-power and high-frequency electronics like RF amplifiers for 5G and radar systems. Further, GaN’s efficient light emission in the blue spectrum makes it a valuable material for LEDs.
Silicon Carbide (SiC)
Silicon carbide (SiC) is a highly attractive material for power electronics due to its excellent thermal conductivity (a material’s ability to transfer heat) and high breakdown voltage (the maximum voltage a material can withstand before electrical current flows uncontrollably). This combination of properties allows SiC to operate efficiently at high voltages and currents, making it ideal for power switches and converters used in various power electronics applications. SiC is also gaining traction in electric vehicles for on-board chargers and inverters, enabling faster charging times and improved efficiency.
Indium Phosphide (InP)
Indium phosphide (InP) is valued for its excellent optical properties and high electron mobility. These properties make it a desirable material for high-speed optical communication devices like lasers and detectors used in fibre optic networks. InP is also used in microwave components as it can handle high frequencies.
Aluminum Gallium Indium Phosphide (AlGaInP):
Aluminum Gallium Indium Phosphide (AlGaInP) is an alloy. This combination of elements allows engineers to tune the material’s bandgap. By adjusting each element’s proportion in the final alloy, AlGaInP can be made to emit light in different colours, particularly red and orange. This makes it a valuable material for light-emitting diodes (LEDs).
How Do Compound Semiconductors Perform Compared To Silicon?
Compound semiconductors offer several performance advantages over silicon in specific applications, as described below:
Strengths
- Higher Electron Mobility: Electrons move faster in compound semiconductors compared to silicon. This translates to:
- Faster Switching Speeds: This is crucial for high-frequency electronics like RF amplifiers in 5G and radar systems.
- Lower Power Consumption: Faster electron movement can lead to more efficient operation in certain devices.
- Wider Bandgap: This allows some compound semiconductors to handle higher voltages and operate at higher temperatures without breaking down. This makes them ideal for:
- High-Power Electronics: Materials like SiC excel in power converters and switches used in electric vehicles and renewable energy systems.
- Light Emission: GaN’s wider bandgap allows for efficient blue LEDs, a key component for white LEDs and displays.
- Unique Optical Properties: Certain compounds like InP emit light efficiently at specific wavelengths, making them valuable for lasers and detectors used in fibre optic communication.
Weaknesses
- Manufacturing Complexity: Compound semiconductors can be more challenging and expensive to manufacture due to complex growth processes.
- Cost: The higher manufacturing complexity translates to a higher per-unit cost compared to silicon.
Are Compound Semiconductors The Future Of Semiconductors?
Compound semiconductors are strong contenders for the future of electronics but not a clear-cut solution to replace silicon entirely. The following is a breakdown of why they hold promise and the challenges they face:
Why Compound Semiconductors Shine
- Addressing Silicon’s Limits: As chip miniaturisation approaches physical limitations, silicon struggles to maintain performance gains. Compound semiconductors offer ways to overcome these barriers.
- Specialisation For Specific Needs: The ability to tailor properties through material combinations allows for highly specialised and efficient chips for power electronics, high-frequency communication, and optoelectronics.
- Emerging Applications: The rise of electric vehicles, renewable energy systems, and advanced communication technologies like 5G creates a strong demand for the capabilities of compound semiconductors.
Challenges To Overcome
- Manufacturing Hurdles: Developing cost-effective and scalable manufacturing processes for compound semiconductors is crucial for adoption.
- Cost Factor: Currently, producing compound semiconductors is more expensive than silicon, limiting their use in price-sensitive applications.
- Material Science Advancements: Further research is needed to explore new compound combinations and improve their performance characteristics to unlock their potential.
Factors To Watch For
- Advancements In Manufacturing: As production techniques for compound semiconductors become more efficient and cost-effective, their adoption will likely increase.
- Government And Industry Investment: Increased funding for research and development can accelerate innovation and bring down production costs for compound semiconductors.
- Technological Advancements: Breakthroughs in material science and chip design could unlock even more potential for compound semiconductors.
