Non-contact carrier density measurement of semiconductor wafers by terahertz spectroscopic ellipsometry

We developed a terahertz ellipsometry system that can measure the complex dielectric characteristics of doped semiconductors and evaluate the carrier density and mobility in a non-destructive, non-contact way. The system is constructed of optical-fiber pigtail-coupled terahertz emitter and detector, and delivers high measurement precision and stability. We demonstrated carrier-density measurement of n-type GaAs wafer and n-type SiC epitaxial film using this system, and confirmed a good agreement with conventional measurement methods.