Diamond——A wonder in the field of functional materials
As a diamond application, it involves a wide range of technologies and is very difficult. It requires cooperative research in various fields to be realized in a relatively short period of time. In the future, it is necessary to continuously develop and improve CVD diamond growth technology and explore the application of CVD diamond film in acoustics, optics, and electricity. It will become a new material for high-tech development in the 21st century. CVD can be used for both engineering materials and functional materials. The following is only an introduction to its functional applications.
What is a functional material? Functional materials refer to various materials with physical and chemical functions such as light, electricity, magnetism, sound, and heat used in industry and technology, including electrical functional materials, magnetic functional materials, optical functional materials, superconducting materials, biomedical materials, functional membranes, etc.
What is a functional membrane? What are its characteristics? Functional membrane refers to a thin film material with physical properties such as light, magnetism, electric filtration, adsorption, and chemical properties such as catalysis and reaction.
Characteristics of thin film materials: Thin film materials are typical two-dimensional materials, that is, they are large on two scales and small on the third scale. Compared with commonly used three-dimensional bulk materials, it has many characteristics in performance and structure. The biggest feature is that some properties of functional films can be achieved through special thin film preparation methods during preparation. This is why thin film functional materials have become a hot topic of attention and research.
As a two-dimensional material, the most important feature of thin film materials is the so-called size feature, which can be used to miniaturize and integrate various components. Many uses of thin film materials are based on this point, the most typical of which is used in integrated circuits and to increase the storage density of computer storage components.
Due to the small size, the relative proportion of the surface and interface in the thin film material is relatively large, and the properties exhibited by the surface are extremely prominent. There are a series of physical effects related to the surface interface:
(1) Selective transmission and reflection caused by the light interference effect;
(2) Inelastic scattering caused by the collision between electrons and the surface causes changes in conductivity, Hall coefficient, current magnetic field effect, etc.;
(3) Because the film thickness is much smaller than the mean free path of electrons and is close to the Drobyi wavelength of electrons, the electrons moving back and forth between the two surfaces of the film will interfere, and the energy related to the vertical movement of the surface will take discrete values, which will affect the electron transport;
(4) On the surface, atoms are periodically interrupted, and the surface energy level and the number of surface states generated are of the same order of magnitude as the number of surface atoms, which will have a great impact on materials with few carriers such as semiconductors;
(5) The number of neighboring atoms of the surface magnetic atoms decreases, causing the magnetic moment of the surface atoms to increase;
(6) Anisotropy of thin film materials, etc.
Since the performance of thin film materials is affected by the preparation process, most of them are in a non-equilibrium state during the preparation process. Therefore, the composition and structure of thin film materials can be changed in a wide range without being restricted by the equilibrium state. Therefore, people can prepare many materials that are difficult to achieve with bulk materials and obtain new properties. This is an important feature of thin film materials and an important reason why thin film materials attract people’s attention. Whether chemical or physical methods are used, the designed thin film can be obtained.
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