Analyses of thin films and surfaces by cold neutron depth profiling

Neutron depth profiling (NDP) has been employed to examine manufacturing processes and starting materials for several high-technology applications. NDP combines nuclear and atomic physics processes to determine the concentration profile of several light elements in the near surface region ( 1–8 mm) of smooth surfaces. The method is both quantitative and nondestructive. Analyses are performed at the Center for Neutron Research at NIST on samples prepared at Corning Incorporated. Two types of samples have been analyzed: (1) Boron profiles are measured in glasses to determine B loss due to its volatilization during manufacturing. Surface depletion of B is a key characteristic of borosilicate materials for both chemical vapor deposition and conventional melting processes. (2) For lithium niobate, a quantitative measure of Li concentration can differentiate congruent and stoichiometric compositions and any surface depletion in commercial wafers