My scientific research work focuses on the fundamental connection between macroscopic properties and atomic-level structure of materials. The methodology of choice is positron annihilation spectroscopy that is particularly suitable for lattice defect characterization in solids. The power of positron spectroscopies lies in (i) the selective sensitivity to open volume structures, (ii) the possibility of studying materials of any type (conductive, insulating, hard, soft, crystalline, or porous) and (iii) the possibility of direct comparison of theoretical calculations and experimental observations. My group is is one of the world’s leading teams in developing the methodology, instrumentation, applications and theory of positron annihilation spectroscopy of semiconductor materials and devices.