Make crystals with LEC method
6/28/2023，published by QSAM inc
Introduction
The LEC (Liquid Encapsulated Czochralski) method is a widely used technique in the manufacturing of high-quality single crystals. This method involves the growth of crystals from a molten solution that is encapsulated by a crucible made of suitable materials. The crystals grown using this technique are used in various applications, such as semiconductor devices, optoelectronics, and high-temperature superconductors.
In this article, we will discuss the LEC method in detail, including its principle, advantages, and disadvantages. Additionally, we will also provide some examples of crystals that have been grown using this method, particularly those utilizing PBN (Pyrolytic Boron Nitride) crucibles.
The Principle of LEC Method
The LEC method involves the melting of a material in a special crucible (usually made of boron nitride or platinum). The crystal growth happens from the bottom of the melt under controlled temperature, pressure, and atmosphere. During the process, the seed crystal is dipped into the melt and then pulled out at a controlled rate. The melted part of the crystal gradually solidifies as it moves away from the melt, leaving behind a pure crystal at the end of the process.
One of the unique features of the LEC method is the use of an encapsulant material (such as boron nitride) to contain and protect the crystal's seed during growth. This allows for the growth of highly pure crystals without contamination from the crucible material, which is especially important when producing semiconductors or electronic components.
Advantages of LEC Method
There are several advantages to using the LEC method over other crystal growing methods. One of the main benefits is the high level of purity achievable with LEC crystals, as mentioned earlier. The use of an encapsulating material like boron nitride also helps protect the seed crystal from contamination or damage during growth.
Another advantage is the excellent quality of the crystal obtained. The LEC method produces a crystal with a smooth surface that is free of cracks, striations, or other defects. This means that crystals grown using this method can be used in applications requiring high-quality surfaces, such as lenses or mirrors.
Disadvantages of LEC Method
Despite its many advantages, there are some drawbacks to using the LEC method, particularly regarding the crucible material and the cost. Boron nitride crucibles are preferred for growing certain types of materials because of their non-reactive
Examples
One example of the LEC method in action is the production of gallium arsenide (GaAs) crystals for use in electronic devices such as solar cells and semiconductors. GaAs crystals grown using the LEC method have excellent structural and electrical properties, making them ideal for use in high-performance electronic applications.
Another example is the production of sapphire crystals that are used in LED manufacturing. Sapphire crystals grown using the LEC method offer exceptional optical clarity and hardness, which makes them an ideal material for producing robust and long-lasting LED lights.
One crucial element in the LEC method is the use of a PBN crucible, or a pyrolytic boron nitride crucible. The PBN LEC crucible acts as a container for the molten material and also helps to shield the crystal from impurities during the growth process. Due to its unique thermal insulation properties, the PBN crucible can withstand high temperatures and maintain a stable temperature environment during crystal growth.
Summary
In summary, the LEC method is an effective way to produce high-quality single crystals for a range of applications. Its ability to produce crystals with exceptional structural and electrical properties has made it a crucial manufacturing technique across various industries. Furthermore, the use of PBN crucibles adds value to the LEC method by enhancing the quality of the final product.