Physical properties of the ferroelectric capacitors based on Al-doped HfO2 grown via Atomic Layer Deposition on Si
| Autor: | Antoniu Moldovan, Nicoleta G. Apostol, S. Vulpe, Sorina Iftimie, F. Nastase, Adrian Dinescu, Mircea Dragoman, Cosmin Romanitan |
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| Rok vydání: | 2019 |
| Předmět: |
Materials science
Silicon Oxide General Physics and Astronomy chemistry.chemical_element 02 engineering and technology 010402 general chemistry 01 natural sciences chemistry.chemical_compound Atomic layer deposition X-ray photoelectron spectroscopy Aluminium Thin film business.industry Surfaces and Interfaces General Chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics Ferroelectricity 0104 chemical sciences Surfaces Coatings and Films Piezoresponse force microscopy chemistry Optoelectronics 0210 nano-technology business |
| Zdroj: | Applied Surface Science. 483:324-333 |
| ISSN: | 0169-4332 |
| DOI: | 10.1016/j.apsusc.2019.03.166 |
| Popis: | Ferroelectric capacitors based on aluminium (Al) doped hafnium oxide (HfO2) thin films grown on silicon substrates were fabricated by Atomic Layer Deposition (ALD), taking into account two methods. The first one involved the growth of a binary oxide, in a laminar way, by alternating the ALD cycles of HfO2 and Al2O3, and the second, the two precursors were sequentially mixed on the surface. The composition and structure of deposited aluminium doped hafnium oxide (Al:HfO2) thin films have been studied using X-ray photoelectron spectroscopy (XPS) and grazing incidence X-ray diffraction (GIXRD). XPS measurements show the formation of opposite ferroelectric polarization areas. Via GIXRD, it was found that the Al:HfO2 films deposited on Si have a structure with polycrystalline domains. Recording and investigation of ferroelectric domains were performed by Piezoresponse Force Microscopy (PFM), while the electrical performances of obtained devices were analysed by capacitance-voltage (C-V) and current-voltage (I-V) characteristics. The PFM measurements show there is a mechanical non-zero response even outside the written area and for an appropriate value of the electrical stress the difference in phase between successive areas is saturated to a value close to 180°. The atomic force microscopy (AFM) analyses indicate a very low value of roughness average, for all grown thin films, ~0.2 nm, for a thickness of ~7 nm. From C-V characteristics, the memory window was extracted and the calculated values were found to be 0.8 V for the device obtained by the first ALD method, and 0.44 V for the second one, respectively. Moreover, in the case of the device based on the ferroelectric layer grown by the second ALD method, the memory window extends over a much wider applied voltage domain, in the range (±4 V; ±8 V), at a signal of 100 kHz. |
| Databáze: | OpenAIRE |
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