（1）Elemental semiconductor. Elemental semiconductor refers to a semiconductor composed of a single element, among which research on silicon and selenium was relatively early. It is a solid material composed of the same elements with semiconductor properties, which is susceptible to changes caused by trace impurities and external conditions. At present, only silicon and germanium have good performance and are widely used, while selenium is applied in the fields of electronic lighting and optoelectronics. Silicon is widely used in the semiconductor industry, mainly influenced by silicon dioxide, which can form masks in device fabrication, improve the stability of semiconductor devices, and facilitate automated industrial production.
　　
　　（2）Inorganic composite semiconductor. Inorganic composites are mainly composed of semiconductor materials made up of a single element, although there are also semiconductor materials made up of multiple elements. The main semiconductor properties include Group I and Groups V, VI, and VII; Group II and Groups IV, V, VI, and VII; III, V, and VI groups; IV and IV/VI groups; V and VI families; VI group and VI group combination compounds, but not all compounds can meet the requirements of semiconductor materials due to the characteristics of the elements and the production method. This semiconductor is mainly used in high-speed devices. Transistors made of InP have higher speeds than other materials and are mainly used in optoelectronic integrated circuits and anti nuclear radiation devices. For materials with high conductivity, they are mainly used in LED and other fields.
　　
　　（3）Organic synthetic semiconductors. Organic compounds refer to compounds containing carbon bonds in their molecules. By stacking organic compounds perpendicular to carbon bonds, a conduction band can be formed. Through chemical addition, it can enter the energy band, resulting in conductivity and the formation of organic compound semiconductors. Compared with previous semiconductors, this semiconductor has the characteristics of low cost, good solubility, and easy material processing. The conductivity can be controlled by controlling molecules, and it has a wide range of applications, mainly used in organic thin films, organic lighting, and other fields.
　　
　　（4）Amorphous semiconductor. It is also known as amorphous semiconductor or glass semiconductor, belonging to a class of materials with semiconductor properties. Amorphous semiconductors, like other amorphous materials, have short-range ordered and long-range disordered structures. It mainly forms amorphous silicon by changing the relative positions of atoms and altering the original periodic arrangement. The main difference between crystalline and amorphous states is whether the atomic arrangement has a long program. The performance control of amorphous semiconductors is difficult, and with the invention of technology, amorphous semiconductors have begun to be used. This production process is simple and mainly used for engineering purposes. It has a good effect on light absorption and is mainly used in solar cells and LCD displays.
　　
　　（5）Intrinsic semiconductor: A semiconductor that does not contain impurities and has no lattice defects is called an intrinsic semiconductor. At extremely low temperatures, the valence band of a semiconductor is full. Upon thermal excitation, some electrons in the valence band will cross the bandgap and enter the high-energy empty band. When electrons exist in the empty band, it becomes the conduction band. If one electron is missing from the valence band, a positively charged vacancy is formed, called a hole. Hole conduction is not an actual motion, but an equivalent. When electrons conduct electricity, holes of equal charge will move in the opposite direction They generate directional motion under the action of an external electric field to form macroscopic currents, known as electron conduction and hole conduction, respectively. This type of mixed conductivity formed by the generation of electron hole pairs is called intrinsic conductivity. Electrons in the conduction band will fall into holes, causing electron hole pairs to disappear, which is called recombination. The energy released during recombination becomes electromagnetic radiation (luminescence) or thermal vibration energy of the lattice (heating). At a certain temperature, the generation and recombination of electron hole pairs coexist and reach dynamic equilibrium, at which point the semiconductor has a certain carrier density and thus a certain resistivity. When the temperature rises, more electron hole pairs will be generated, the carrier density will increase, and the resistivity will decrease. Pure semiconductors without lattice defects have high electrical resistivity and are not widely used in practical applications.