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NTD and NAA

NTD is 'Neutron Transmutation Doping', NAA is 'Neutron Activation Analysis'.

[NRG-Home] > [Products & Services] > [LCI/FI-start] > [NTD and NAA]

Life Cycle innovations & Isotopes / Section FI -
NTD, Neutron Transmutation Doping and NAA, Neutron Activation Analysis

The HFR currently produces neutron transmutation doped (NTD) silicon ingots with a diameter of 4 inch and of 6 inch. Mamximum sample height is 50 cm. The large number of full power days of the HFR (290 per year) and the high flux conditions in the reactor allow for a large production and a fast return shipment of the irradiated ingots.

NRG has successful experience with impurity analysis of silicon ingots using the Neutron Activation Analysis (NAA) technique. This technique can be used to determine the impurities in ultra pure silicon ingots or other high purity materials.

Performance

NRG is able to get very high quality results and low detection limits since:

• The activation is done in the 45 MW High Flux Reactor (HFR). This reactor is operating according a fixed schedule for almost 300 full power days per year. This allows for long activation periods.
• The irradiation is normally done in a position of the HFR with a thermal flux of typically 2*10¹⁷ m^-2s^-1. When a further enhancement of the accuracy is required the activation can also be done in a position with a maximum thermal flux of typically 3*10¹⁸ m^-2s^-1.
• The required cooling period between the end of the irradiation and the start of the analysis is only 2-4 days for high purity silicon.
• The gamma spectrometry measurements are performed using a low back-ground counting facility using a HPGe Well type detector.
• A special procedure is present in order to prevent contamination of the silicon ingots.

In principal, the procedure proposed here gives analytical results for nearly 50 elements. It is expected that real analytical values will be found for only a few of them. The results for the rest will consist of lower limits of detection. Typical detection limits in mg/kg (formerly ppm) will range from 4.10^-3 (4 ppb) for Ca via 2.10^-7 (0.2 ppt) for Cd to 1^-9 (1 ppf) for Au.

Contact

For more information on NAA and NTD, please contact

Dr. Klaas Bakker
NRG - Life Cycle innovations & Isotopes, section NRG-LCI/FI
PO Box 25, 1755 ZG Petten, the Netherlands
phone: +31 224 564362 , fax: +31 224 568608
e-mail: lci@nrg.eu