AFM and Raman studies of topological insulator materials subject to argon plasma etching

• Published in: Philosophical magazine (Abingdon, England) Vol. 93; no. 6; pp. 681 - 689
• Main Authors: Childres, Isaac, Tian, Jifa, Miotkowski, Ireneusz, Chen, Yong
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis Group 01.02.2013; Taylor & Francis
• Subjects: Applied sciences; Argon plasma; Atomic force microscopy; bismuth selenide; bismuth telluride; Crystals; Electronics; Etching; Etching and cleaning; Exact sciences and technology; Exposure; Insulators; Materials; Microelectronic fabrication (materials and surfaces technology); Molecular electronics, nanoelectronics; Physics; Physics of gases, plasmas and electric discharges; Physics of plasmas and electric discharges; Plasma applications; plasma etching; Raman spectroscopy; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Surface roughness; topological insulator; Topology; Atomic force microscopy; Raman spectra; Bismuth Selenides tellurides; Fluctuations; Roughness; Plasma assisted processing; Etching rate; Raman spectroscopy; Nanoelectronics; Thickness; Bismuth selenides; Bismuth tellurides; Topological insulator; Microelectronic fabrication; Plasma etching; Antimony tellurides
• ISSN: 1478-6435; 1478-6443
• DOI: 10.1080/14786435.2012.728009

Plasma etching is an important tool in nano-device fabrication. We report a study on argon plasma etching of topological insulator materials Bi 2 Se 3 , Bi 2 Te 3 , Sb 2 Te 3 and Bi 2 Te 2 Se using exfoliated flakes (with starting thicknesses of ∼100 nm) derived from bulk crystals. We present data mainly from atomic force microscopy (AFM) and Raman spectroscopy. Through AFM measurements, plasma exposure is observed to decrease the thickness of our samples and increase surface roughness (with height fluctuations reaching as large as ∼20 nm). We extract an etching rate for each type of material. Plasma exposure also causes a widening (especially ) of the characteristic Raman peaks, with no significant change in peak position. The overall Raman intensity is observed to initially increase then decrease sharply after the samples are etched below ∼20 nm in thickness. Our findings are valuable for understanding the effects of argon plasma etching on topological insulator materials.