Subsurface damage in ultra-finely finished semiconductors

Ultraprecision finishing of the II-VI semiconductors, some of which have applications in infrared optics (CdS, ZnSe) and as potential substrates for short wavelength light emitters (ZnO, ZnSe), poses particular challenges due to the unique chemical and structural properties of these materials. Studies on their ultrafine surface finishing have demonstrated the achievement of superior surface finish and form accuracy. However, the introduction of subsurface lattice disorder persists and may pose severe limitations on both surface performance and, for substrate applications, their suitability for subsequent epitaxial growth.

We are currently using Rutherford backscattering in the channeling configuration to study the nature, extent and distribution of subsurface damage in finely finished surfaces of single crystal CdS, ZnSe and ZnO. Surfaces prepared by single point diamond turning, and mechanical and chemomechanical polishing have been studied in terms of the total amount of lattice disorder and damage depth. Results from cross-sectional transmission electron microscopy (XTEM) are being used to confirm the amount of lattice disorder and damage depths inferred by our ion channeling studies.

Funding provided by:

NSF and OCAST

Collaborators:

M. Nastasi, C.J. Wetteland and A. Misra, Los Alamos National Laboratory

Relevant publication:

Lucca, D.A., Shao, L., Wetteland, C.J., Misra, A., Klopfstein, M.J. and Nastasi, M., "Subsurface Damage in (100) ZnSe Introduced by Mechanical Polishing", Nuclear Instruments and Methods in Physics Research B, 250, (2006) 907-910.

Lucca, D.A., Wetteland, C.J., Misra, A., Klopfstein, M.J., Nastasi, M., Maggiore, C.J. and Tesmer, J.R., "Assessment of Subsurface Damage in Polished II-VI Semiconductors by Ion Channeling", Nuclear Instruments and Methods in Physics Research B, 219-220, (2004) 611-617.