What is a Dopant?
The doping process is essentially an oxidation or reduction process of the conductive polymer. The oxidant or reducing agent used is called a dopant during the doping process [1] .
- Chinese name
- Dopant
- Foreign name
- dopant
- Classification
- p-type, n-type
- Explanation
- Oxidant or reducing agent during doping
- The doping process is essentially an oxidation or reduction process of the conductive polymer. The oxidant or reducing agent used is called a dopant during the doping process [1] .
Introduction to Dopants
- A dopant having an oxidizing ability is called a p-type dopant and is an electron acceptor; in contrast, a dopant having a reducing ability is called an n-type dopant and is an electron donor. The main p-type dopants include iodine -based halogen elements, high-valent metal compounds of halogen elements, and perchloric acid and nitrates of certain metals. The n-type dopants are mainly alkali metals and organic compounds represented by sodium , potassium , and lithium .
- The dopant can be in a gaseous state, a liquid state, or a solution state during use, and the corresponding doping processes are called vapor-phase doping, liquid-phase doping, and solution doping, respectively. [1]
- A small amount of substance added to the metal powder in order to prevent or control the recrystallization or grain growth of the sintered body during sintering or during use. Mainly used in tungsten powder metallurgy.
Dopant doping process
- Doping device
- 1. Add dopant: close the ball valve 10 and ball valve 11, open the funnel cover, add small granular dopants to the lower part of the funnel body, close the funnel cover and tighten with a hinge bolt to seal, open the ball valve 11 and fill the N2 to make the funnel The air in the body is fully exhausted from the relief valve, and the ball valve 11 [2] is closed.
- 2. Move above the liquid surface: open the locking shaft 7 and turn the handwheel 6 to move the whole system along the guide column 18 into the furnace to the lower limit block 25 [2]
- 3. Doping: Open the ball valve 10, and the small particulate dopant slides into the crucible along the doping tube 1 under the action of gravity. If a small amount of dopant gets stuck and cannot slide down, open the ball valve 11 and fill it with N2 Blow into the furnace and close the ball valve 10 [2] after doping (observed from the observation port on the funnel cover).
- 4. Retreat: Turn the handwheel 6 in the opposite direction to move the entire system outside the furnace along the guide column 18 to the upper limit block 24, close the locking shaft 7, and complete the doping once.
Current status of dopants semiconductor dopants
- In device manufacturing, dopants are an essential requirement and are used in various silicon wafer processing steps from crystal growth to chemical vapor deposition. Dopants are used to change the electrical characteristics of the base material or deposited film. Of particular interest are two key processes, namely diffusion and ion implantation processes [3] .
- According to the characteristics of the dopant atom, the electrical characteristics of silicon are changed, so that the doped silicon or the P-type material has holes as majority carriers or the n-type material (electrons are majority carriers). Diffusion and ion implantation are two competing processes that introduce impurity atoms into silicon. Diffusion process is an older traditional method of doped silicon. These two technologies are finding a favorable position in the silicon wafer process [3] .
- Although many elements are used as dopants, the role of boron and phosphorus is more important. Boron is the P-type dopant of silicon, and phosphorus is the n-type dopant of silicon. Other common doped d elements are arsenic and antimony, because they have high solubility and low diffusion constant, so they are used for doped buried layers. These commonly used dopants are provided in their elemental form or as compounds in any of the three phases (gas, liquid or solid). The choice of dopant compounds and their phases is related to many parameters, not just the equipment used for the doping process. As far as the application of dopants is concerned, two factors that should be noticed are the purity of the dopant material and the danger brought about by the use of special dopant compounds [3] .