Magneto-Optic Ellipsometry

Abstract

The free-charge-carrier properties effective mass m, mobility μ, and carrier concentration N are of fundamental importance for understanding basic material properties of semiconductors. N, m, and μ intriguingly combine concepts of classical (such as the effective “inertial” carrier mass) and quantum physics (e.g., the electron energy-momentum dispersion and the electron band occupation). A long term goal has been the accurate and simultaneous measurement of N, m, and μ by non-contact optical means in materials, which are part of complex layered systems, such as semiconductor heterostructures. The effective mass concept addressed here descends from the similarity with the acceleration of a body with mass m and the acceleration experienced by a free electron (or hole) due to an external force. In general, the thereby obtained effective mass is a tensor and depends on the inverse curvature of the electron energetic states versus electron-momentum dispersion (m) _ij ≈(d²E/dk_idk_j^-1[1].