Explanation

A thin film formed of semiconductor materials. Generally, materials with bandgap width less than 2eV are called semiconductors. The electric conductivity varies with the band gap width at room temperature. As the electrons in the full band of thermal excitation (or photoexcitation, electrical excitation, etc.) enter the conduction band, holes appear in the full band, and electrons appear in the conduction band. Both holes and electrons are charge carriers. When there are impurities, the impurity energy level appears in the band gap. If the impurity atom can give electrons, its energy level is the donor energy level, and the semiconductor is an n-type semiconductor. If impurity atoms can accept electrons, their energy level is the acceptor energy level, and the semiconductor is a P-type semiconductor. A semiconductor materials is the main materials for microelectronic and optoelectronic devices. Especially, the integration of components on large-scale integrated circuit chips is getting higher and higher, and the size of components is getting smaller and smaller? Semiconductor thin films are the basic materials for such devices.? With different technologies for preparing semiconductor films, they can be divided into single crystal, polycrystal and amorphous films in terms of structure. In molecular beam epitaxy technology, superlattice thin films with periodic arrangement can be grown alternatively by epitaxial growth, which become the basic materials of M-sub electronic devices. polycrystal semiconductor films are composed of grains with certain size distribution. The orientation of these grains is randomly distributed. The atoms in the grain are arranged periodically. There are a lot of defects at the grain boundary, which forms a polycrystal semiconductor film with different electrical and optical properties. When the arrangement of atoms in a film is ordered in the short range and disordered in the long range, it is called an amorphous semi conducting film.

Classification