The correct answer is: C. Epitaxial growth.
Epitaxial growth is a process of crystal growth in which a thin film of material is deposited on a substrate in such a way that the crystal structure of the film is identical to that of the substrate. This is in contrast to other methods of film deposition, such as sputtering or chemical vapor deposition, in which the film may have a different crystal structure than the substrate.
Epitaxial growth is often used in the semiconductor industry to create thin films of semiconductor materials with specific properties. For example, epitaxial growth can be used to create layers of silicon with different doping levels, which can be used to create transistors with different electrical properties.
The process of epitaxial growth can be divided into two steps: nucleation and growth. In the nucleation step, the first few atoms of the film are deposited on the substrate. These atoms then form a nucleus, which is a small cluster of atoms that has the same crystal structure as the substrate. Once a nucleus has formed, the growth step can begin. In the growth step, more atoms are deposited on the substrate, and they attach to the nucleus and grow into the film.
There are a number of different methods that can be used to deposit atoms on a substrate during epitaxial growth. The most common method is vapor deposition, in which the atoms are vaporized and then deposited on the substrate. Other methods include molecular beam epitaxy (MBE) and atomic layer deposition (ALD).
The properties of the film that is grown by epitaxial growth depend on a number of factors, including the type of material that is being deposited, the temperature of the substrate, and the pressure of the deposition chamber. By controlling these factors, it is possible to grow films with a wide range of properties.
Epitaxial growth is a versatile and powerful technique that is used in a wide variety of applications. It is particularly important in the semiconductor industry, where it is used to create thin films of semiconductor materials with specific properties.