Effects of polishing processes on the photoluminescence of ZnO

Final polishing of semiconductor substrates is known to introduce near surface lattice disorder and possible changes in surface stoichiometry. These unwanted changes to the near surface have been shown to contribute to the growth of poor epitaxial films and resulting short lifetime devices. We are currently investigating changes in the optical performance of ZnO surfaces which result from the introduction of defects or changes in surface stoichiometry caused by polishing. In particular, we are using low temperature photoluminescence (PL) spectroscopy to study various shifts in the PL spectra caused by different polishing techniques. Our studies to date have demonstrated significant changes in PL response for various surface preparation processes including the introduction of new luminescence peaks. For example, for mechanically polished surfaces we have observed the occurrence of a donor-acceptor pair peak which we have attributed to donors and acceptors which result from point defects introduced by dislocation motion.

Funding provided by:

NSF and OCAST

Collaborators:

M. Nastasi, C. J. Wetteland, J. R. Tesmer, Los Alamos National Laboratory

Relevant publications:

Hamby, D. W., Lucca, D. A. and Klopfstein, M. J., "Photoluminescence of Mechanically Polished ZnO", Journal of Applied Physics, 97, (2005) 043504.

Hamby, D. W., Lucca, D. A., Klopfstein, M. J. and Cantwell, G., "Temperature Dependent Exciton Photoluminescence of Bulk ZnO", Journal of Applied Physics, 93, (2003) 3214-3217.

Lucca, D. A., Hamby, D. W., Klopfstein, M. J. and Cantwell, G., "Chemomechanical Polishing Effects on the Room Temperature Photoluminescence of Bulk ZnO: Exciton-LO Phonon Interaction", physica status solidi (b), 229, (2002) 845-848.

Lucca, D. A., Hamby, D. W., Klopfstein, M. J., Cantwell, G., Wetteland, C. J., Tesmer, J. R. and Nastasi, M., "Effects of Polishing on the Photoluminescence of Single Crystal ZnO", Annals of the CIRP, 50, (2001) 397-400.