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Neutron Transmutation Doping of Silicon

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Summary

The MIT-NRL Silicon Program uses neutron transmutation doping (NTD) of single crystal silicon at the MIT Research Reactor (MITR-II) to create free electrons (low resistivity). The process takes place when undoped silicon is irradiated in a thermal neutron flux and the Si-31 atom transmutes to a P-31 atom, resulting in a lower resistivity with little variance from the target resistivity. The silicon crystals are loaded into 400mm magnesium cans and then transferred to the airlock, pushed through the through port, and placed on a conveyor for radioactive decay. After being irradiated, the ingots are inspected for quality control before being packaged and shipped to the customer.

Q&As

What is neutron transmutation doping of silicon?
Neutron transmutation doping of silicon is a process in which undoped (high purity) silicon is irradiated in a thermal neutron flux.

What are the through ports used for?
The through ports are used for Neutron Transmutation Doping (NTD) of single crystal silicon at the MIT Research Reactor (MITR-II).

What is the purpose of semiconductor doping?
The purpose of semiconductor doping is to create free electrons (low resistivity).

How are the silicon crystals loaded?
The silicon crystals are loaded into 400 mm long magnesium cans and then placed on the loading conveyor.

What happens to the silicon ingots after irradiation?
After irradiation, the silicon ingots are removed from the conveyor, carefully cleaned, surveyed for radiation, and inspected for quality control before being packaged and shipped to the customer.

AI Comments

👍 This article provides a comprehensive overview of the Neutron Transmutation Doping process. It also outlines the process in detail, with a great description of the steps involved in the process from loading to unloading and radioactive decay.

👎 The article does not address any potential safety concerns or risks of radiation exposure associated with Neutron Transmutation Doping.

AI Discussion

Me: It's about Neutron Transmutation Doping (NTD) of silicon. Basically, it's a process where silicon is irradiated with thermal neutrons, which are captured by the 30Si atom, and then transmuted to a P-31 atom. This lowers the resistivity of the material, which is used in a variety of electronic devices.

Friend: Wow, that's really interesting. What are the implications of this?

Me: Well, this process could have a big impact on the semiconductor industry, since it makes it easier to produce materials with low resistivity. It could also lead to the production of more efficient electronic devices, since they would require less power to operate. Additionally, it could potentially reduce costs since it's a more efficient process.

Action items

Research the process of Neutron Transmutation Doping (NTD) and its applications in the semiconductor industry.
Learn more about the MIT Research Reactor (MITR-II) and its capabilities for NTD of single crystal silicon.
Explore the various types of magnesium cans used for the loading and unloading of silicon crystals for NTD.

Technical terms

Neutron Transmutation Doping (NTD): A process in which undoped (high purity) silicon is irradiated in a thermal neutron flux. The thermal neutron is captured by the 30Si atom, which has a 3% abundance in pure Si, and the Si-31 atom transmutes to a P-31 atom, resulting in a lower resistivity with little variance from the target resistivity.
MIT Research Reactor (MITR-II): A nuclear reactor located at the Massachusetts Institute of Technology (MIT) used for research and development.
4TH1-3 and 6TH1-2 horizontal through ports: Two ports located tangent to the D2O Reflector Tank at the MIT Research Reactor (MITR-II) used for Neutron Transmutation Doping (NTD) of single crystal silicon. The 4TH1-3 port can accommodate the 4-inch crystals and the 6TH1-2 port can accommodate 4, 5 and 6-inch crystals.
Magnesium cans: 400 mm long cans used to hold the silicon crystals during the Neutron Transmutation Doping (NTD) process.
Airlock: A chamber located at the MIT Research Reactor (MITR-II) used to transfer the magnesium cans containing the silicon crystals from the loading conveyor to the through port.
Loading conveyor: A conveyor belt located at the MIT Research Reactor (MITR-II) used to transfer the magnesium cans containing the silicon crystals to the airlock.
Unload side: The side of the through port at the MIT Research Reactor (MITR-II) where the magnesium cans containing the silicon crystals are transferred to the unload conveyor.
Unload conveyor: A conveyor belt located at the MIT Research Reactor (MITR-II) used to transfer the magnesium cans containing the silicon crystals from the unload side of the through port.
Radiation: The emission of energy in the form of waves or particles.
Quality control: The process of ensuring that products and services meet certain standards of quality.