- 作者： Alfassi, Zeev B.
- 作者服務機構： Dept. of Nuclear Engineering, Ben Gurion Univ., Beer Sheva, Israel
- 中文摘要：
Activation analysis in general and mainly reactor neutron activation analysis (NAA) has been used extensively for measuring trace elements in high purity materials, particularly semiconductor materials. The advantages of NAA in determination of trace elements differ from one semiconductor material to another. For all of them the inherent properties of activation analysis especially those of non contamination with the reagents, low blanks and high sensitivity are the reasons for the choice of NAA as the main analytical procedure. These inherent properties are essential for analysis of high-purity materials where concentrations of ppb's and sub ppb's have to be measured.
NAA is especially suitable for the determination of trace elements in silicon due to the very short lived very low activity induced by neutron reaction in silicon. This enables easy instrumental (i.e. without chemical separations) determination of trace elements in silicon. In the HFR reactor at Peten, Netherlands, a special facility was constructed for irradiation of silicon samples of Philips, in which silicon wafers of up to 15cm diameter can be irradiated with 4*10/sup 13/n-cm/sup -2/-sec/sup -1/ and the irradiation is done for 72-96 hours. Using large Ge(Li) detector (100 to 150cc) and long counting time (8-16 hours), they measured 22 elements in concentrations below ppb and 10 others between ppb and 300ppm. Trace elements in germanium have been determined both instrumentally after very long decay time (100 days) or after short decay time removing the activities from the matrix by chemical separation. Trace elements in GaAs are determined only after chemical separation. Several other semiconductor material such as Se, Te, GaP and CuInS/sub 2/ were also determined by NAA.
Some trace elements cannot be determined by neutron activation. Carbon, nitrogen and oxygen are determined by activation with protons, alphas or /sup 3/He particles. Boron and hydrogen are determined by prompt emission induced by charged particle activation, which gives not only the total concentration but also the depth profile. Carbon, nitrogen, oxygen and phosphorus were also determined by prompt proton activation analysis.
The environmental samples studied by activation analysis can be divided into three categories: atmospheric aerosols, water samples and solid wastes. NAA of atmospheric aerosols have been used for their possible toxicological hazards, their source identification and for studies of atmospheric transport processes. - 英文摘要： --
- 中文關鍵字： Activation Analysis; Material Science; Environmental Science; Neutron Reaction; Semiconductor
- 英文關鍵字： 活化分析；材料科學；環境科學；中子反應；半導體
