Doping Definition: In a pure semiconductor that forms a crystal structure, artificially doping a very small amount of a specific impurity element will cause a significant change in its electrical conductivity. Principle: In the crystal structure of semiconductors, the original number of carriers (electrons or holes) is small, and the conductivity is weak. When doped with impurities, the impurity atoms will combine with atoms in the semiconductor lattice, changing the energy band structure of the semiconductor and thus affecting the number and distribution of carriers. For example, in the silicon or germanium single crystal doped with phosphorus (or other pentavalent elements), the number of free electrons can be increased substantially, the formation of n-type semiconductors; doped with boron (or other trivalent elements), the formation of a large number of holes, the formation of p-type semiconductors. Application: This property can be used to produce a variety of different uses of semiconductor devices, such as diodes, transistors, thyristors, etc., is the semiconductor is widely used as an important basis.
Thermal Sensitivity Definition: The electrical conductivity of a semiconductor increases significantly as the temperature of the external environment increases. Principle: Atomic vibrations in semiconductor crystals are intensified at elevated temperatures, which makes it easier for carriers (electrons or holes) to gain energy and thus be able to move more easily through the crystal, resulting in increased conductivity. For intrinsic semiconductors, the effect of temperature on their electrical conductivity is even more pronounced, since the carriers in intrinsic semiconductors are mainly generated by thermal excitation. Applications: Based on the thermal sensitivity can be made into temperature sensitive components, such as thermistors, which are used for temperature measurement, control and compensation. It has a wide range of applications in overheating protection and temperature monitoring of electronic devices.
Photosensitivity Definition: Semiconductors under light conditions undergo significant changes in their electrical conductivity. Principle: When the semiconductor material is irradiated by light of a certain wavelength, the energy of the photon is absorbed by the semiconductor, which excites the electrons to jump from the valence band to the conduction band, generating electron - cavity pairs, thus increasing the concentration of carriers and increasing the conductivity of the semiconductor. Different semiconductor materials have different responses to different wavelengths of light, e.g. cadmium sulphide is sensitive to visible light, lead sulphide and indium antimonide are sensitive to infrared light. Application: Using photosensitivity can make a variety of photosensitive components, such as photoresistors, photosensitive diodes, photosensitive transistors, etc., widely used in optical communications, optoelectronic automatic control, image recognition, solar cells and other fields.
Negative Resistivity Temperature Characteristics Definition: Generally speaking, the resistance of a conductor increases with increasing temperature, showing a positive temperature coefficient; while semiconductors in a certain temperature range, its resistance decreases with increasing temperature, showing a negative temperature coefficient. Principle: This is due to the conductive mechanism of semiconductors is different from that of conductors. Semiconductor carriers in the production and movement of the temperature is closely related to the temperature, the temperature increases the carrier concentration increases faster than the carrier mobility decreases, thus making the semiconductor resistance decreases. Applications: This characteristic has important applications in semiconductor temperature sensors, thermistors and other devices, which can be used to achieve accurate measurement and control of temperature by using their negative resistivity temperature characteristics.
Definition: Semiconductors have the property of unidirectional conductivity, i.e., they have a directionality to the conduction of current. Principle: The pn junction formed in a semiconductor is the key structure to realise the rectification property. When a forward voltage is applied to both ends of the pn junction, the holes in the p-region and the electrons in the n-region will diffuse into each other's region, forming a large forward current, and the pn junction is in a state of conduction; when a reverse voltage is applied, the electrons in the p-region and the holes in the n-region are pulled back to their respective regions, and there is only a small reverse saturation current in the pn junction, which is almost non-conducting. Application: Based on the rectifier characteristics can be made rectifier diodes, rectifier bridges and other rectifier devices, used to convert alternating current into direct current, in the power adapter, charger, power supply circuits for electronic equipment, etc. are widely used.
