Pulsed laser deposition technique was used for the fabrication of Ge-Te rich GeTe-Sb2Te3 (Ge6Sb2Te9, Ge8Sb2Te11, Ge10Sb2Te13, and Ge12Sb2Te15) amorphous thin films. To evaluate the influence of GeTe content in the deposited films on physico-chemical properties of the GST materials, scanning electron microscopy with energy-dispersive X-ray analysis, X-ray diffraction and reflectometry, atomic force microscopy, Raman scattering spectroscopy, optical reflectivity, and sheet resistance temperature dependences as well as variable angle spectroscopic ellipsometry measurements were used to characterize as-deposited (amorphous) and annealed (crystalline) layers. Upon crystallization, optical functions and electrical resistance of the films change drastically, leading to large optical and electrical contrast between amorphous and crystalline phases. Large changes of optical/electrical properties are accompanied by the variations of thickness, density, and roughness of the films due to crystallization. Reflectivity contrast as high as ~0.21 at 405 nm was calculated for Ge8Sb2Te11, Ge10Sb2Te13, and Ge12Sb2Te15 layers.

Department of Graphic Arts and Photophysics Faculty of Chemical Technology University of Pardubice Studentská 573 53210 Pardubice Czech Republic

Equipe Verres et Céramiques UMR CNRS 6226 Sciences Chimiques de Rennes Université de Rennes 1 35042 Rennes Cedex France

Institut de Chimie de la Matière Condensée de Bordeaux CNRS 87 av du Dr Albert Schweitzer 33608 Pessac Cedex France

See more in PubMed

Kolobov A. V. et al.. Understanding the phase-change mechanism of rewritable optical media. Nat. Mater. 3, 703–708 (2004). PubMed

Wuttig M. & Yamada N. Phase-change materials for rewriteable data storage. Nat. Mater. 6, 824–832 (2007). PubMed

Raoux S., Welnic W. & Ielmini D. Phase change materials and their application to nonvolatile memories. Chemical Reviews 110, 240–267 (2010). PubMed

Wuttig M. & Raoux S. The science and technology of phase change materials. Z. Anorg. Allg. Chem. 638, 2455–2465 (2012).

Lencer D., Salinga M. & Wuttig M. Design rules for phase-change materials in data storage applications. Adv. Mater. 23, 2030–2058 (2011). PubMed

Yamada N. Origin, secret, and application of the ideal phase-change material GeSbTe. Phys. Status Solidi B-Basic Solid State Phys. 249, 1837–1842 (2012).

Raoux S. & Wuttig M. Phase Change Materials. (Springer, 2009).

Ovshinsky S. R. Reversible Electrical Switching Phenomena in Disordered Structures. Phys. Rev. Lett. 21, 1450–1453 (1968).

Friedrich I., Weidenhof V., Njoroge W., Franz P. & Wuttig M. Structural transformations of Ge2Sb2Te5 films studied by electrical resistance measurements. J. Appl. Phys. 87, 4130–4134 (2000).

Wuttig M. et al.. The role of vacancies and local distortions in the design of new phase-change materials. Nat. Mater. 6, 122–127 (2007). PubMed

Welnic W. & Wuttig M. Reversible switching in phase-change materials. Materials Today 11, 20–27 (2008).

Lencer D. et al.. A map for phase-change materials. Nat. Mater. 7, 972–977 (2008). PubMed

Akola J. & Jones R. O. Structure of amorphous Ge8Sb2Te11: GeTe-Sb2Te3 alloys and optical storage. Phys. Rev. B 79, 134118 (2009).

Buller S. et al.. Influence of Partial Substitution of Te by Se and Ge by Sn on the Properties of the Blu-ray Phase-Change Material Ge8Sb2Te11. Chem. Mat. 24, 3582–3590 (2012).

Yamada N. et al.. In Optical Data Storage 2001 Vol. 4342 Proceedings of the Society of Photo-Optical Instrumentation Engineers (SPIE) (eds Hurst T. & Kobayashi S.) 55–63 (The International Society for Optical Engineering, 2001).

Krbal M. et al.. Local atomic order of crystalline Ge8Sb2Te11 across the ferroelectric to paraelectric transition: The role of vacancies and static disorder. Phys. Rev. B 84, 104106 (2011).

Matsunaga T. et al.. Structural characteristics of GeTe-rich GeTe-Sb2Te3 pseudobinary metastable crystals. J. Appl. Phys. 103, 093511 (2008).

Jost P. et al.. Disorder-Induced Localization in Crystalline Pseudo-Binary GeTe-Sb2Te3 Alloys between Ge3Sb2Te6 and GeTe. Adv. Funct. Mater. 25, 6399–6406 (2015).

Akola J. & Jones R. O. Density functional study of amorphous, liquid and crystalline Ge2Sb2Te5: homopolar bonds and/or AB alternation? J. Phys.-Condes. Matter 20, 465103 (2008). PubMed

Caravati S., Bernasconi M., Kuhne T. D., Krack M. & Parrinello M. Coexistence of tetrahedral- and octahedral-like sites in amorphous phase change materials. Appl. Phys. Lett. 91, 171906 (2007).

Park J. W. et al.. Optical properties of (GeTe, Sb2Te3) pseudobinary thin films studied with spectroscopic ellipsometry. Appl. Phys. Lett. 93, 021914 (2008).

Lee B. S. et al.. Investigation of the optical and electronic properties of Ge2Sb2Te5 phase change material in its amorphous, cubic, and hexagonal phases. J. Appl. Phys. 97, 093509 (2005).

Garcia-Garcia E. et al.. Optical properties of Ge : Sb : Te ternary alloys. Journal of Vacuum Science & Technology A-Vacuum Surfaces and Films 17, 1805–1810 (1999).

Orava J. et al.. Optical properties and phase change transition in Ge2Sb2Te5 flash evaporated thin films studied by temperature dependent spectroscopic ellipsometry. J. Appl. Phys. 104, 043523 (2008).

Abrutis A. et al.. Hot-wire chemical vapor deposition of chalcogenide materials for phase change memory applications. Chem. Mat. 20, 3557–3559 (2008).

Choi B. J. et al.. Cyclic PECVD of Ge2Sb2Te5 films using metallorganic sources. J. Electrochem. Soc. 154, H318–H324 (2007).

Ritala M. et al.. Atomic layer deposition of Ge2Sb2Te5 thin films. Microelectronic Engineering 86, 1946–1949 (2009).

Olivier M. et al.. Photosensitivity of pulsed laser deposited Ge-Sb-Se thin films. Optical Materials Express 5, 781–793 (2015).

Nemec P. et al.. Ge-Sb-Te thin films deposited by pulsed laser: An ellipsometry and Raman scattering spectroscopy study. J. Appl. Phys. 106, 103509 (2009).

Hawlova P., Verger F., Nazabal V., Boidin R. & Nemec P. Photostability of pulsed laser deposited amorphous thin films from Ge-As-Te system. Scientific Reports 5, 9310 (2015). PubMed PMC

Nemec P., Prikryl J., Nazabal V. & Frumar M. Optical characteristics of pulsed laser deposited Ge-Sb-Te thin films studied by spectroscopic ellipsometry. J. Appl. Phys. 109, 073520 (2011).

Nemec P. et al.. Amorphous and crystallized Ge-Sb-Te thin films deposited by pulsed laser: Local structure using Raman scattering spectroscopy. Mater. Chem. Phys. 136, 935–941 (2012).

Andrikopoulos K. S. et al.. Raman scattering study of the a-GeTe structure and possible mechanism for the amorphous to crystal transition. J. Phys.: Condens. Matter 18, 965–979 (2006).

Mazzarello R., Caravati S., Angioletti-Uberti S., Bernasconi M. & Parrinello M. Signature of tetrahedral Ge in the Raman spectrum of amorphous phase-change materials. Phys. Rev. Lett. 104, 085503 (2010). PubMed

Sosso G. C., Caravati S., Mazzarello R. & Bernasconi M. Raman spectra of cubic and amorphous Ge2Sb2Te5 from first principles. Phys. Rev. B 83, 134201 (2011). PubMed

Caravati S., Bernasconi M. & Parrinello M. First-principles study of liquid and amorphous Sb2Te3. Phys. Rev. B 81, 014201 (2010).

Steigmeier E. F. & Harbeke G. Soft phonon mode and ferroelectricity in GeTe. Solid State Commun. 8, 1275–1279 (1970).

Kato T. & Tanaka K. Electronic properties of amorphous and crystalline Ge2Sb2Te5 films. Jpn. J. Appl. Phys. Part 1 - Regul. Pap. Brief Commun. Rev. Pap. 44, 7340–7344 (2005).

Weidenhof V., Friedrich I., Ziegler S. & Wuttig M. Atomic force microscopy study of laser induced phase transitions in Ge2Sb2Te5. J. Appl. Phys. 86, 5879–5887 (1999).

Wamwangi D., Njoroge W. K. & Wuttig M. Crystallization kinetics of Ge4Sb1Te5 films. Thin Solid Films 408, 310–315 (2002).

Van der Pauw L. J. A method of measuring specific resistivity and Hall effect of discs of arbitrary shape. Philips Research Reports 13, 1–9 (1958).

Cody G. D. In Semiconductors and semimetals Vol. 21B (ed Pankove J. I.) 11 (Academic, 1984).

Nemec, P. et al.. Photo-stability of pulsed laser deposited GexAsySe100−x−y amorphous thin films. Opt. Express 18, 22944–22957 (2010). PubMed

Arsenic-Doped SnSe Thin Films Prepared by Pulsed Laser Deposition

Comparative study of Er3+-doped Ga-Ge-Sb-S thin films fabricated by sputtering and pulsed laser deposition

Mass spectrometric investigation of amorphous Ga-Sb-Se thin films

Ge-Sb-Te Chalcogenide Thin Films Deposited by Nanosecond, Picosecond, and Femtosecond Laser Ablation