At the beginning of the twentieth century, the principles of modern science and technology were continuously used to control the crystal growth process, and crystal growth began to evolve from art to science. Especially since the 1950s, the development of semiconductor materials represented by single crystal silicon has promoted the development of crystal growth theory and technology. In recent years, the development of a variety of compound semiconductors and other electronic materials, optoelectronic materials, nonlinear optical materials, superconducting materials, ferroelectric materials, and metal single crystal materials has led to a series of theoretical problems. And more and more complex requirements are put forward for crystal growth technology. The research on the principle and technology of crystal growth has become increasingly important and has become an important branch of modern science and technology.
At present, crystal growth has gradually formed a series of scientific theories, which are used to control the crystal growth process. However, this theoretical system is not yet perfect, and there is still a lot of content that depends on experience. Therefore, artificial crystal growth is generally considered to be a combination of craftsmanship and science.
The preparation of complete crystals requires the following conditions:
1.The temperature of the reaction system should be controlled uniformly. In order to prevent local overcooling or overheating, it will affect the nucleation and growth of crystals.
2. The crystallization process should be as slow as possible to prevent spontaneous nucleation. Because once spontaneous nucleation occurs, many fine particles will be formed and hinder crystal growth.
3. Match the cooling rate with the crystal nucleation and growth rate. The crystals are grown uniformly, there is no concentration gradient in the crystals, and the composition does not deviate from chemical proportionality.
Crystal growth methods can be classified into four categories according to the type of their parent phase, namely melt growth, solution growth, vapor phase growth and solid phase growth. These four types of crystal growth methods have evolved into dozens of crystal growth techniques with changes in control conditions.
In general, if the whole process of crystal growth is decomposed, it should at least include the following basic processes: dissolution of solute, formation of crystal growth unit, transport of crystal growth unit in growth medium, crystal growth The movement and combination of the element on the crystal surface and the transition of the crystal growth interface, so as to realize the crystal growth.
Post time: Dec-07-2022