A semiconductor is a material that is electrically and physically intermediate between a conductor and an insulator. Its electrical conductivity is affected by a variety of factors, including factors such as the applied electric field, temperature,semiconductor testing and impurities within the material. Semiconductors have a variety of unique properties, some of which include:

1. Non-Linear Resistance Properties: The resistance of a semiconductor varies with voltage and is not linear. This is due to the presence of multiple electron orbitals and energy levels within the semiconductor material, and the electrons jumping between the energy levels generates a current, which leads to a change in resistance.

2. Conductivity of electrons and holes: There are two types of carriers in semiconductor materials, negatively charged electrons and positively charged holes. These two types of carriers move in the presence of an electric field, leading to the conductivity of the material.

3. Photoelectron effect: Semiconductor materials can produce electrical or optical signals when stimulated by incident light. This phenomenon is known as the photoelectric effect and is one of the underlying principles in many electronic devices.

4. PN junction: PN junction is one of the most basic structures in semiconductor devices, which is made by combining P-type semiconductors and N-type semiconductors through a specific process.PN junctions have a variety of functions,semiconductor failure analysis such as rectifying and converting electrical signals.

5. Temperature sensitivity: The conductivity of semiconductors changes with temperature. Within a certain temperature range, the resistance of semiconductor materials decreases as the temperature increases.

In addition to the above characteristics, semiconductors also have other unique characteristics, such as the forbidden band width of semiconductor materials, carrier diffusion, simplicity and so on. These properties make semiconductors an indispensable material in today's electronic technology.

However, the properties of semiconductors do not include the following:

1. Chemical properties: Semiconductor materials are not very different from other materials in terms of chemical properties, and their reactions and properties with other materials depend on the specific composition and make-up of the semiconductor.

2. mechanical properties: the mechanical properties of semiconductor materials such as strength,aotomatic prober toughness, etc. is not its unique characteristics, the mechanical properties of semiconductor devices depends mainly on the hardness and toughness of the material.

3. magnetic properties: semiconductor materials are generally not magnetic, its properties in the magnetic field and other materials are not significantly different.

In short, the characteristics of semiconductors include nonlinear resistance properties, electron and hole conductivity, photoelectron effect, PN junction, temperature sensitivity and many other aspects. These properties make semiconductors one of the most widely used materials in today's electronic technology, with applications in a wide range of fields including electronics, optoelectronics, and semiconductor lasers.