Study of the Effect of Various Chemical Polishing Treatments on MBE-Grown CdTe/GaAs (211)B Heterostructures

Year 2020, Volume: 24 Issue: 6, 1232 - 1247, 01.12.2020

Elif Bilgilisoy Elif Özçeri Enver Tarhan

https://doi.org/10.16984/saufenbilder.748315

Abstract

A three-inch-diameter high quality CdTe thin film was grown on a GaAs (211)B substrate by molecular beam epitaxy (MBE) in ultra-high vacuum conditions. The CdTe/GaAs (211)B heterostructure was then cut into several sample pieces. A few as-grown sample pieces were subjected to chemical etching solutions which created etch pits on the surface. The scanning electron microscopy images of such samples were used to calculate the etch pit densities on the surface. In addition, several as-grown samples were subjected to chemical polishing treatments under different conditions to quantify the removal of O and Te-O structures from the surface. Atomic force microscopy was used to determine as-grown and polished surface morphology and the polish rate of chemical solutions. A study of the surface stoichiometry and the chemical composition of the as-grown and polished CdTe (211)B surfaces were carried out by using X-ray photoelectron spectroscopy. Bulk structural qualities of the as-grown and polished samples were studied in terms of the vibrational and phonon modes via confocal Raman spectroscopy. From a comparative analyses of the results, the best chemical polishing conditions for the MBE-grown CdTe (211)B heterostructure were determined.

Keywords

Molecular beam epitaxy, CdTe thin film, GaAs substrate, thin film polishing, XPS, Raman spectroscopy, AFM

Thanks

We would like to thank Orhan Öztürk for his help in XRD measurements. We are also thankful to Gülnur Aygün and Lütfi Özyüzer for the help they provided especially with the XPS measurements. Additionally, we thank IYTE Material Research Center staff, especially Emine Bakali, for obtaining SEM images. We are deeply grateful to Yusuf Selamet who played a pivotal role in all the studies mentioned in this work. Finally, we are grateful to SSM (Undersecretariat for Defence Industries of Turkey) and ASELSAN for their financial support.

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