1. Photosensitivity The resistivity of a semiconductor is very sensitive to changes in light. In the presence of light, the resistivity is small; in the absence of light, the resistivity is large. For example, commonly used cadmium sulfide photosensitive resistors, in the absence of light, the resistance up to several tens of megaohms, when exposed to light. The resistance drops to several tens of kiloohms all at once and the resistance value changes thousands of times. Using the photosensitivity of semiconductors, various types of optoelectronic devices such as photodiodes, phototransistors, and silicon photocells have been fabricated. Widely used in automatic control and radio technology.

2. Doping characteristics In a pure semiconductor, doping a very small amount of impurity elements will cause a great change in its resistivity. E.g. In pure silicon, one part per million of boron is added, and its resistivity decreases from 214,000 Ω·cm to 0.4 Ω·cm. That is, the conductivity of silicon has increased by more than 500,000 times. It is through the incorporation of certain specific impurity elements that artificially precisely controls the conductivity of semiconductors to produce different types of semiconductor devices. It is no exaggeration to say that almost all semiconductor devices are made of semiconductor materials doped with specific impurities.

3. Thermal Characteristics The resistivity of a semiconductor changes significantly with temperature. For example, pure germanium, its humidity increases by 10 degrees, its resistivity should be reduced to 1/2 of the original. Subtle changes in temperature can be reflected in the apparent change in semiconductor resistivity. Using the heat-sensitive properties of semiconductors, temperature sensing elements - thermistors - can be fabricated for use in temperature measurement and control systems. It is worth noting that various semiconductor devices have thermal characteristics and affect the stability of their operation when the ambient temperature changes.