Phoenix redundant module 2320173 has monitoring function

Phoenix redundant module 2320173 has monitoring function

Impurities in semiconductors have a significant impact on electrical resistivity. When trace impurities are doped into semiconductors, the periodic potential field near the impurity atoms is disturbed and additional binding states are formed, resulting in the generation of impurity energy levels in the bandgap. For example, tetravalent elements germanium or siliconcrystalWhen pentavalent elements such as phosphorus, arsenic, antimony, etc. are doped into the lattice, the impurity atom acts as a molecule of the lattice. Four of its five valence electrons form covalent bonds with surrounding germanium (or silicon) atoms, and the excess electron is bound near the impurity atom, producing a hydrogen like energy level. The impurity energy level is located above the bandgap near the bottom of the conduction band. Electrons at impurity levels are easily excited to the conduction band and become electron carriers. This impurity that can provide electron carriers is called a donor, and the corresponding energy level is called a donor energy level. The energy required for electrons on the donor level to transition to the conduction band is much smaller than the energy required for excitation from the valence band to the conduction band (Figure 2). When trace amounts of trivalent elements such as boron, aluminum, gallium, etc. are doped into germanium or silicon crystals, the impurity atoms form covalent bonds with the surrounding four germanium (or silicon) atoms and lack an electron, resulting in a vacancy. The energy state corresponding to this vacancy is the impurity energy level, usually located below the bandgap near the valence band. Electrons in the valence band are easily excited to fill the vacancy at the impurity level, causing the impurity atom to become a negative ion. A hole carrier is formed in the valence band due to the absence of an electron. This type of impurity that can provide holes is called an acceptor impurity. When there are acceptor impurities present, the energy required to form a hole carrier in the valence band is much smaller than in the case of intrinsic semiconductors. After semiconductor doping, its resistivity greatly decreases. Heating or light induced thermal or optical excitation can increase the number of free charge carriers and lead to a decrease in resistivity in semiconductorsthermistorandphotoresistorIt is made based on this principle.

Phoenix redundant module 2320173 has monitoring function