Electrical Measurements and Nuclear Activation Techniques for Radiation Damage Studies and Impurity Analysis in Silicon and in Laser Materials

摘要

The most favorable nuclear method for detecting carbon, nitrogen and oxygen in silicon at the parts per million level (ppm) was determined to be charged particle activation. A sputtering mass spectrography offers potential for ppm detection as well. Infrared techniques detect only that fraction of the impurity which is properly located in the laltice to contribute to the infrared vibration while nuclear techniques and mass spectrography detect all the impurity present. The uniformity of dopants in an Al spectroscopic standard has been studied for the dopants Mn, Ga, and Cu by neutron activation. For 100 micro-gram samples a standard deviation of 2% was determined for the method. Within this error Mn and Ga were found to be uniformly distributed while the Cu was not. Recent advances in electro probe analysis appears to make this method more desirable than nuclear activation because with nuclear techniques interfering activities limit the number of impurities that can be determined. Techniques for fabrication of Hall bars for radiation damage studies were developed. A P.M.E. null technique was improved by use of a blue argon laser in order to measure lifetimes below one micro-sec. in silicon Hall samples. A laser test facility was constructed for rare earth doped materials. Gamma ray activation was developed for analyzing for trace amounts of samarium, gadolinum, neodymium and cerium. (Author)