The PIs propose the acquisition of a state-of-the-art cathodoluminescence instrument which will enable nano-scale resolution optical measurements in-situ in a Scanning Electron Microscope (SEM). The Gatan MonoCL3 system for high-resolution cathodoluminescence (CL) imaging and spectroscopy will be integrated into a Philips XL3O TMP SEM operating in the PI's laboratory. The SEM by itself has been extensively employed in Electron Beam Induced Current (EBIC) and in-situ electrical measurements of III-Nitride nanostructures. The cathodoluminescence setup is critical, since it provides nanoscale information on optical properties, composition, and defect distribution.
The CL instrument is equipped with a high efficiency collector, which is optimized for the SEM, and transfers light to an integrated spectrometer. Therefore, CL signals at the single photon level can be detected and low electron beam currents be used. The spatial resolution in CL measurements is determined by the range (penetration depth) of electrons from the SEM beam in the material, which depends on the accelerating voltage. Thus, a sampling range of 10 nm is achieved in III-Nitrides with a voltage of ~ 1 keV.
The cathodoluminescence spectroscopy system will significantly enhance cross-departmental research projects focused on III-Nitride semiconductors and novel materials. These include studies of the fundamental effects, induced by electron injection in GaN and related compounds, as well as device applications. For instance, the efficiency of GaN photodetectors is determined by minority carrier transport, which will be investigated by combining in-situ electrical and cathodoluminescence measurements in the SEM.
The broader impact of the new equipment will be the deeper understanding of electron interaction with semiconductors and nanostructrures as well as the integration of research and education in the graduate and undergraduate learning environment. Acquisition of the CL system will foster several research programs in advanced materials, which are currently funded or under consideration for funding, as well as partnership with industry. Drs. Chernyak and Schulte have established major activity [I -9] related to the "UV-Florida" program, which unites efforts of Uniroyal Optoelectronics and several Florida Universities, including the University of Central Florida, in the development of efficient A1GaN-based multiple quantum well light emitting diodes. Since Uniroyal has specifically expressed an interest in the proposed cathodoluminescence setup, there are clear benefits for this academia-industry partnership.
The new instrumentation enables outstanding research and education opportunities for students in nanoscale experimental techniques. The "UV-Florida" program currently supports 5 graduate students whose rotations have been coordinated by the PI. It is anticipated that at least 15 more faculty and students (including undergraduates) will use the equipment. Knowledge of the state-of-the-art cathodoluminescence applications will broaden the students' career options with the high-tech companies in the Central Florida 14-corridor.
