Materials Science and Chemistry

Biography

Biography: Leonard J. Brillson

Abstract

Spatially-resolved cathodoluminescence spectroscopy has contributed significant new information to our understanding of native point defects in ZnO micro- and nanoscale structures. This presentation will review representative examples of this work and the new perspectives gained from spatially resolving these defects both laterally and depth-wise. Results obtained from many groups worldwide include studies of Schottky diodes, polycrystalline, ceramics, nanostructures, and microwires. The nature and spatial distribution of native point defects in these materials together with their strong dependence on growth and processing suggest new avenues for their control in transport and optoelectronic device structures. A key aspect of ZnO-based materials and applications is the nature, spatial distribution, and electronic impact of native point defects. These features are particularly important at the micro- and nanoscale, where their physical properties can dominate charge carrier transport and electronic contacts. Starting from the optical identification of specific defects already discussed in the literature, this talk focuses on the new defect information provided by spatially-localized cathodoluminescence spectroscopy (CLS). This technique has unique advantages in measuring key defect features. Spatially-resolved CLS has now shown that: (1) native point defects are present inside these structures and not just on their surfaces; (2) their nature and distribution depend on the specific growth method used to create them; and (3) they can strongly affect nanoscale transport and device properties. These studies suggest many new avenues to understand and control defects in ZnO and may be of more general significance as spatially-resolved cathodoluminescence spectroscopy extends to other semiconductors and device structures.