In recent years, the development of Moore’s Law has limited the progress of traditional silicon-based semiconductors. However, with the urgent need for development in 5G communication, automotive electronics, and optical communication, the search for the next-generation semiconductor has become imperative. Compound semiconductor materials, with their high electron mobility, direct bandgap, and wide energy band, perfectly match the needs of the next-generation semiconductor development, and the era of compound semiconductors is gradually approaching.
Compound semiconductors have unique properties and are widely used to replace silicon-based semiconductors in various applications.
Although, the current global semiconductor chips and devices, which account for over 95% of the market, are still mainly produced using silicon as the base functional material for silicon-based semiconductors. However, with the advent of the Internet of Things and 5G era, compound semiconductors such as gallium arsenide (GaAs), gallium nitride (GaN), and silicon carbide (SiC) are rapidly gaining popularity.
Such new application scenarios as the RF module of 5G base stations, optical communication, wireless communication systems in smartphones, and VSECL broad-beam sources for 3D Sensing, as well as millimeter wave radar for autonomous driving, will all be key areas of focus and growth drivers for compound semiconductor applications.
What is commonly known as compound semiconductor is a semiconductor material made of compounds, usually consisting of more than two elements. There are many ways to combine these elements, which provides more room for imagination. Depending on the material properties, various components such as those resistant to high temperature, high voltage, radiation, and those capable of emitting light can be designed. These components can then be further developed and applied in various specific fields.
Such as gallium nitride (GaN), due to its lower sensitivity to electromagnetic radiation, makes GaN-based components highly stable in radiation environments. This also allows GaN transistors to operate at high temperatures and high voltages, making them ideal power amplifier components for microwave frequencies.
As for the material of SiC, it is similar to GaN in having low resistance and high frequency, as well as being able to withstand high temperatures. However, SiC has a higher efficiency than GaN, and with the cost gradually decreasing, it is widely used in power control applications in the market and has become another main development direction.
Additionally, in the part of compound semiconductor gallium arsenide (GaAs) that is most familiar to us today, the microwave components produced mainly include HBT (heterojunction bipolar transistor), PHEMT (pseudo-heterojunction high-speed electron-moving transistor), and MESFET (metal-semiconductor field-effect transistor).
Because of its high power and high linearity, which are required for carrier aggregation and multi-input multi-output (MIMO) technology, gallium arsenide (GaAs) is a key component in the current stage of rapid adoption of 5G communication, including mobile communication, wireless local area network (WLAN), and radar systems for autonomous vehicles. It will also be the mainstream technology in the 6GHz以下 frequency band.
3D Sensing opens the door to facial recognition applications on smartphones.
In the application of compound semiconductors, it primarily focuses on power control, wireless communication, infrared, solar energy, and optical communication. Among the most well-known applications, those that stand out include 3D Sensing, LiDAR/radar equipment for autonomous vehicle assistance systems, and applications for vehicle power.
The 3D Sensing component originated in 2017 with the use of a vertical cavity surface-emitting laser (VCSEL) as the core component in a 3D Sensing camera lens, which was used in the 10th-anniversary model of Apple’s iPhone for the user’s face recognition (FACE ID) function and subsequently sparked a global trend of smartphones adopting 3D Sensing camera lenses. Among the components of the 3D Sensing camera lens, there are gallium arsenide (GaAs) VCSEL chips manufactured using compound semiconductors.
Self-driving cars paired with LiDAR systems provide a foundation for safe self-driving.
While the application of 3D Sensing is prominent, the recently emerging self-driving cars in the automotive market have also become a major consumer of compound semiconductor products. The composition conditions for self-driving car control include sensors, positioning, computing and control, and precise maps, among which sensors mainly consist of four types of cameras, ultrasonic sensors, millimeter wave radar, and lidar.
In addition to 3D Sensing applications for in-vehicle facial recognition and gesture recognition, compound semiconductors are mainly used in the LiDAR and radar devices for advanced driving assistance systems (ADAS) in vehicles, as well as in the power control systems for electric vehicles.
In the LiDAR part, the use of Time of Flight (TOF) technology is employed, where the vehicle emits a very short pulse (~10 ns, 10-8 seconds) of laser to illuminate the target, and also initiates a fast timer for time measurement. When the light sensor receives the reflected echo signal from the target, it stops the timer’s timing, and the distance between the vehicle and the object is measured by the time it takes for the light to travel. The principle is similar to that of automotive radar, but the difference lies in that LiDAR can identify objects, while radar can only sense distance.
In the application of LiDAR, VCSEL laser elements produced from gallium arsenide, a high-power and high-linearity semiconductor compound, play a crucial role. By emitting laser beams onto a target and then receiving the reflected beams through a receiver, LiDAR systems can function and operate effectively.
Compound semiconductors have a promising future not only in the field of autonomous vehicles, but also in the current automotive chip sector. Due to the demanding operating environment (high temperature, high frequency, and high power), as well as the need to work with the inductors and capacitors in automotive circuits, automotive components tend to be larger in size compared to conventional components.
However, by utilizing the characteristics of compound semiconductors, including gallium nitride and silicon carbide, it will be possible to achieve a reduction in the size of automotive components. Therefore, by replacing silicon semiconductors with gallium nitride and silicon carbide, it is gradually becoming possible to reduce the energy consumption of automotive components during switching.
In this regard, BMW, which has been relentlessly developing advanced driving technologies for cars, points out that the vast majority of its new models now come standard with Personal CoPilot intelligent driving assistance technology.
This smart driving assistance technology, which utilizes compound semiconductor components, is a complete set of active and passive driving assistance systems for consumers, including features such as automatic cruise control, lane departure warning system, blind spot detection system, rear traffic assistance system, front traffic assistance system, or intersection detection functions, along with automatic parking assistance, to achieve advanced driving capabilities.
While in addition to adopting compound semiconductor components in the driving system, the advancement of compound semiconductor technology has enabled the improvement of battery performance, the density of the battery can be increased, the capacity of the battery can be increased for the same volume, and the overall battery cost can be reduced, which can drive down the vehicle price of electric vehicles. Therefore, BMW also believes that it is expected that the electric vehicle market will have a very vigorous development in the next 10 years.
It is certain that since the 3D Sensing technology driven by Apple’s iPhone has been given more attention, the non-Apple camp has accelerated its adoption of 3D Sensing, driving up demand for VCSELs and thus increasing the importance of compound semiconductors. Additionally, the electric vehicle market is expected to continue to grow at a modest pace, driving demand for power semiconductor devices used in cars, and thus boosting the revenue growth of compound semiconductors.
Additionally, the demand for LiDAR components in advanced driver assistance systems is increasing year by year, driving up the demand for compound semiconductor-based components. Overall, the widespread adoption of these markets is expected to be a major driver of continued growth in the compound semiconductor market.