Characterization of defects in semiconductors using radioactive isotopes

Radioactive atoms have been used in solid-state physics and in material science for many decades. Besides their classical application as tracer for diffusion studies, nuclear techniques such as Mossbauer spectroscopy, perturbed angular correlation, and emission channeling have used nuclear properties to gain microscopical information on the structural and dynamical properties of solids. The availability of many different radioactive isotopes as a clean ion beam at facilities like ISOLDE/CERN has triggered a new era involving methods sensitive for the optical and electronic properties of solids, especially in the field of semiconductor physics. Spectroscopic techniques like photoluminescence (PL), deep-level transient spectroscopy (DLTS), and Hall effect gain a new quality by using radioactive isotopes. Due to their decay the chemical origin of an observed electronic and optical behavior of a specific defect or dopant can be unambiguously identified. This contribution will highlight a few examples to illustrate the potential of radioactive isotopes for solving various problems connected to defects in semiconductor physics.