Impact of Etch Processes on the Chemistry and Surface States of the Topological Insulator Bi2Se3
| Autor: | Paul K. Hurley, Christopher R. Cormier, Christopher L. Hinkle, Rafik Addou, Adam T. Barton, Robert M. Wallace, Xiaoye Qin, Lee A. Walsh, Christopher M. Smyth |
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| Rok vydání: | 2019 |
| Předmět: |
Materials science
Photoemission spectroscopy Etch chemistry Angle-resolved photoemission spectroscopy 02 engineering and technology 010402 general chemistry 01 natural sciences Process integration chemistry.chemical_compound X-ray photoelectron spectroscopy Etching (microfabrication) Sputtering General Materials Science Surface states Topological insulator business.industry technology industry and agriculture 021001 nanoscience & nanotechnology Dirac cone 0104 chemical sciences Bismuth selenide chemistry Optoelectronics 0210 nano-technology business |
| Zdroj: | ACS Applied Materials & Interfaces. 11:32144-32150 |
| ISSN: | 1944-8252 1944-8244 |
| DOI: | 10.1021/acsami.9b10625 |
| Popis: | The unique properties of topological insulators such as Bi2Se3 are intriguing for their potential implementation in novel device architectures for low power and defect-tolerant logic and memory devices. Recent improvements in the synthesis of Bi2Se3 have positioned researchers to fabricate new devices to probe the limits of these materials. The fabrication of such devices, of course, requires etching of the topological insulator, in addition to other materials including gate oxides and contacts which may impact the topologically protected surface states. In this paper, we study the impact of He+ sputtering and inductively coupled plasma Cl2 and SF6 reactive etch chemistries on the physical, chemical, and electronic properties of Bi2Se3. Chemical analysis by X-ray photoelectron spectroscopy tracks changes in the surface chemistry and Fermi level, showing preferential removal of Se that results in vacancy-induced n-type doping. Chlorine-based chemistry successfully etches Bi2Se3 but with residual Se–Se bonding and interstitial Cl species remaining after the etch. The Se vacancies and residuals can be removed with postetch anneals in a Se environment, repairing Bi2Se3 nearly to the as-grown condition. Critically, in each of these cases, angle-resolved photoemission spectroscopy (ARPES) reveals that the topologically protected surface states remain even after inducing significant surface disorder and chemical changes, demonstrating that topological insulators are quite promising for defect-tolerant electronics. Changes to the ARPES intensity and momentum broadening of the surface states are discussed. Fluorine-based etching aggressively reacts with the film resulting in a relatively thick insulating film of thermodynamically favored BiF3 on the surface, prohibiting the use of SF6-based etching in Bi2Se3 processing. |
| Databáze: | OpenAIRE |
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