Synthesizing High-Purity Silicon Carbide Powder

How does SiC achieve its prominence in the semiconductor field? 

It is primarily due to its exceptional wide bandgap characteristics, ranging from 2.3 to 3.3 eV, which make it an ideal material for manufacturing high-frequency, high-power electronic devices. This feature can be likened to constructing a broad highway for electronic signals, ensuring smooth passage for high-frequency signals and laying a solid foundation for more efficient and rapid data processing and transmission.

Its wide bandgap, ranging from 2.3 to 3.3 eV, is a key factor, making it ideal for high-frequency, high-power electronic devices. It's as if a vast highway has been paved for electronic signals, allowing them to travel unimpeded, thus establishing a robust basis for enhanced efficiency and speed in data handling and transfer.

Its high thermal conductivity, which can reach 3.6 to 4.8 W·cm⁻¹·K⁻¹. This means it can quickly dissipate heat, acting as an efficient cooling "engine" for electronic devices. Consequently, SiC performs exceptionally well in demanding electronic device applications that require resistance to radiation and corrosion. Whether facing the challenge of cosmic ray radiation in space exploration or dealing with corrosive erosion in harsh industrial environments, SiC can operate stably and remain steadfast.

Its high carrier saturation mobility, ranging from 1.9 to 2.6 × 10⁷ cm·s⁻¹. This feature further broadens its application potential in the semiconductor domain, effectively enhancing the performance of electronic devices by ensuring the swift and efficient movement of electrons within the devices, thus providing strong support for achieving more powerful functionalities.

How has the history of SiC (silicon carbide) crystal material development evolved? 

Looking back at the development of SiC crystal materials is like turning the pages of a book of scientific and technological progress. As early as 1892, Acheson invented a method for synthesizing SiC powder from silica and carbon, thus initiating the study of SiC materials. However, the purity and size of the SiC materials obtained at that time were limited, much like an infant in swaddling clothes, though possessing infinite potential, still needed continuous growth and refinement.

It was in 1955 when Lely successfully grew relatively pure SiC crystals through sublimation technology, marking an important milestone in the history of SiC. However, the SiC plate-like materials obtained from this method were small in size and had large performance variations, much like a group of uneven soldiers, finding it difficult to form a strong fighting force in high-end application fields.

It was between 1978 and 1981 when Tairov and Tsvetkov built upon Lely's method by introducing seed crystals and carefully designing temperature gradients to control material transport. This innovative move, now known as the improved Lely method or seed-assisted sublimation (PVT) method, brought a new dawn for the growth of SiC crystals, significantly enhancing the quality and size control of SiC crystals, and laying a solid foundation for the widespread application of SiC in various fields.

What are the core elements in the growth of SiC single crystals? 

The quality of SiC powder plays a crucial role in the growth process of SiC single crystals. When using β-SiC powder to grow SiC single crystals, a phase transition to α-SiC may occur. This transition affects the Si/C molar ratio in the vapor phase, much like a delicate chemical balancing act; once disrupted, the crystal growth can be adversely affected, similar to the instability of a foundation leading to the tilt of an entire building.

They mainly come from the SiC powder, with a close linear relationship existing between them. In other words, the higher the purity of the powder, the better the quality of the single crystal. Therefore, preparing high-purity SiC powder becomes the key to synthesizing high-quality SiC single crystals. This requires us to strictly control the impurity content during the powder synthesis process, ensuring that every "raw material molecule" meets high standards to provide the best foundation for crystal growth.

What are the methods for synthesizing high-purity SiC powder? 

Currently, there are three main approaches to synthesizing high-purity SiC powder: vapor phase, liquid phase, and solid phase methods.

It cleverly controls the impurity content in the gas source, including CVD (Chemical Vapor Deposition) and plasma methods. CVD utilizes the "magic" of high-temperature reactions to obtain ultra-fine, high-purity SiC powder. For example, using (CH₃)₂SiCl₂ as the raw material, high-purity, low-oxygen nano silicon carbide powder is successfully prepared in a "furnace" at temperatures ranging from 1100 to 1400℃, much like meticulously sculpting exquisite works of art in the microscopic world. Plasma methods, on the other hand, rely on the power of high-energy electron collisions to achieve high-purity synthesis of SiC powder. Using microwave plasma, tetramethylsilane (TMS) is used as the reaction gas to synthesize high-purity SiC powder under the "impact" of high-energy electrons. Although the vapor phase method can achieve high purity, its high cost and slow synthesis rate make it akin to a highly skilled craftsman who charges a lot and works slowly, making it difficult to meet the demands of large-scale production.

The sol-gel method stands out in the liquid phase method, capable of synthesizing high-purity SiC powder. Using industrial silicon sol and water-soluble phenolic resin as raw materials, a carbothermal reduction reaction is carried out at high temperatures to ultimately obtain SiC powder. However, the liquid phase method also faces the issues of high cost and a complex synthesis process, much like a road full of thorns, which, although it can reach the goal, is full of challenges.

Through these methods, researchers continue to strive to improve the purity and yield of SiC powder, promoting the growth technology of silicon carbide single crystals to higher levels.

Semicorex offers High-purity SiC Powder for semiconductor processes. If you have any inquiries or need additional details, please don't hesitate to get in touch with us.

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