Application of Near-Field Optics to Semiconductor Materials Characterization
Abstract
This grant supported a program for local spectroscopic studies of semiconductor nanostructure materials. Our work has looked at the various types of techniques of near field optics and pursued the options that are optimized for the optical spectroscopy of semiconductor nanostructures. The thrust of the research has involved the use of solid immersion lenses. This form of near field optics strikes a balance between the need for high spatial resolution and high optical throughput. We have demonstrated that these techniques can be implemented within the context of a cryogenic system and obtain spatial resolution of order lambda3. We have used these techniques to characterize naturally occurring quantum dots in thin GaAs quantum wells. Our studies reveal the surprising fact that these samples have not only zero dimensional excitons but also two dimensional excitons. In fact, most of the material plays host to the two dimensional species while the zero dimensional species occupies only 1-3% of the sample. This result is surprising because all of the light emission comes from the zero dimensional exciton. The two dimensional exciton is observed using photoluminescence excitation diffusion, a technique wherein we are able to generate a local optical excitation and watch it diffuse.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 20, 1999
- Accession Number
- ADA369939
Entities
People
- Robert D. Grober
Organizations
- Yale University