Identify the microscopic mechanism underlying cooling-dependent active-donor profiles

Determine whether the lower extrapolated Hall-derived active-donor intercept and broader profile observed after long cooling arise from lithium redistribution, precipitation, electrically inactive lithium-related complex formation, compensation, lithium out-diffusion, surface reactions, source-loading variation, or artifacts of the Hall-depth-profiling method, using complementary chemical and electrical measurements.

Background

The study finds that long post-diffusion cooling is associated with a lower extrapolated apparent active-donor intercept and a broader low-concentration tail than short cooling. The authors list several physically distinct explanations, including continued lithium diffusion during cooling, precipitation or complex formation, compensation, lithium loss, source-loading variation, and measurement artifacts.

Because the Hall-depth-profiling method measures a mobility-weighted electrically active-donor quantity rather than total lithium concentration, the reported profiles alone cannot identify which mechanism, or combination of mechanisms, produces the observed changes. The authors indicate that secondary-ion mass spectrometry combined with electrical profiling, capacitance–voltage profiling, spreading-resistance profiling, differential Hall profiling, and detector charge-collection or dead-layer measurements would be needed to resolve the issue.