Optical probe for surface and subsurface defects induced by ion bombardment.

L D Sun,M Hohage,P Zeppenfeld

doi:10.1002/pssr.201307088

L D Sun, M Hohage + Show 1 more

Open Access

https://doi.org/10.1002/pssr.201307088

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Abstract

We demonstrate that reflectance difference spectroscopy (RDS) is sensitive to defects induced by ion bombardment, located either in the topmost layer or in the subsurface region. Most importantly, these two kinds of defects can be spectrally discriminated, since the corresponding signatures in the RD spectrum arise from perturbations of different types of electronic states: The defects in the topmost surface layer mainly lead to a quenching of the optical anisotropy related to surface states, whereas the subsurface defects strongly affect the optical anisotropy originating from transitions between surface-modified bulk electronic states. Consequently, RDS can be used to simultaneously monitor the defects in the topmost surface layer and in the subsurface region in-situ during ion bombardment and thermal annealing.Characteristic RD spectra and the corresponding STM images for a Cu(110) substrate before and after healing of the subsurface defects.

Highlights

Rare gas ion bombardment and subsequent thermal annealing is routinely used to prepare clean and smooth surfaces for surface studies and subsequent thin film growth
The optical discrimination is based on the fact that the defect-induced perturbation of the optical anisotropy is different for the defects in the topmost layer and in the subsurface region
The completely different behavior of the Reflectance difference spectroscopy (RDS) signal at 2.1 eV can be related to the surface morphology induced by ion bombardment at the corresponding temperatures

Summary

Introduction

Rare gas ion bombardment and subsequent thermal annealing is routinely used to prepare clean and smooth surfaces for surface studies and subsequent thin film growth. We apply RDS as a sensitive probe to defects formed in the topmost surface layer as well as in the subsurface region during ion bombardment.

Results

Conclusion