Alin Velea

Paul Scherrer Institute, Villigen, .

E-mail: trimite un mesaj.

Pagina web a instituţiei: http://www.psi.ch
Pagina web personala: http://old.infim.ro/~velea

Urmareste linkul ResearcherID pentru toate articolele cercetatorului: B-9033-2011. Tabelul detaliat al articolelor este in josul paginii.

Nascut(a) in: 1984

Interese: Phase Change Materials, Amorphous Chalcogenides, X-ray Spectroscopy, X-ray Diffraction

Detalii:
Postdoc: Institutul Paul Scherrer, Elvetia, 2013 – prezent
- Studiul tranzitiei de la faza amorfa la faza cristalina in straturi subtiri suprapuse de materiale calcogenice folosind tehnici de sincrotron:
o Studii de difractie de radiatii X si spectroscopie de radiatii X pe straturi subtiri simple (GeTe, SnSe si GaSb) si suprapuse (GeTe/SnSe, GeTeGaSb si SnSe/GaSb), tratate si netratate termic, creeate prin metoda depunerii laser pulsate;
o Investigarea in-situ a cristalizarii si inter-difuziei in straturile subtiri simple si suprapuse;
o Studiul cristalizarii straturilor subtiri cu schimbare de faza simple si suprapuse tratate termic la diferite temperaturi folosind microscopia electronica de baleiaj.

Cercetator Stiintific: Institutul National De Cercetare-Dezvoltare pentru Fizica Materialelor, Romania, 2008-2013
- Studiul proprietatilor luminescente ale trisulfurii de arsen dopate cu pamanturi rare;
- Investigarea proprietatilor de senzor ale straturilor subtiri Langmuir-Blodgett dopate cu nanotuburi de carbon;
- Studiul difuziei argintului in trisulfura de arsen sub actiunea luminii ultraviolete, verde si alba;
- Microlentile din trisulfura de arsen si cristale fotonice obtinute prin iradierea cu laserul in femtosecunde a straturilor subtiri amorfe de trisulfura de arsen obtinute prin evaporare termica;

Doctorat: Universitatea din Bucuresti, Romania, 2008-2011
- Studiul materialelor cu schimbare de faza din sistemele Ge – Sb –Te si Sn – Se, dopate si nedopate, cu aplicatii in stocarea informatiei;t
- Modelarea procesului de tranzitie in materialele cu schimbare de faza calcogenice folosind tehnici ca Monte Carlo si Automate Celulare;
- Simularile au aratat ca defectele joaca un rol decisiv in viteza de comutare, concetratia optima de defecte fiind in jurul valorii de 25%;
- Exeperimentele au demonstrat ca doparea cu argint a materialelor studiate conduce la o crestere semnificativa a energiei de activare a cristalizarii.

Details:
Postdoc: Paul Scherrer Institute, Switzerland, 2013 – present
- Study of phase change in stacked chalcogenide thin films using synchrotron techniques:
o X-ray diffraction and X-ray spectroscopy studies of as-deposited and annealed pulsed laser deposited monolayers of GeTe, SnSe and GaSb, and double layers of GeTe/SnSe, GeTeGaSb and SnSe/GaSb;
o In situ investigations of crystallization and layer inter-diffusion of amorphous chalcogenide mono and double layers;
o Study of crystallization of mono and double phase change layers annealed at different temperatures by scanning electron microscopy.

Scientific Researcher: National Institute of Materials Physics, Romania, 2008-2013
- Study of the luminescent properties of rare earth doped arsenic trisulphide thin films;
- Investigations on the sensing properties of carbon nanotubes functionalized Langmuir - Blodgett layers;
- Silver diffusion study in arsenic trisulphide matrix obtained by ultraviolet, green light and broadband light irradiation of As2S3/Ag heterostructures;
- Arsenic trisulphide microlenses and photonic structures obtained through femtosecond laser irradiation of vacuum thermal deposited/pulsed laser deposited As2S3 thin films.

Doctoral Research: National Institute of Materials Physics, Romania, 2008-2011
- Study of undoped and metal doped chalcogenide phase change materials from the Ge – Sb –Te and Sn – Se systems for applications in data storage;
- Cellular Automata and Monte Carlo modelling of the switching process in chalcogenide phase change materials;
- Simulations showed that the defects in the material have a decisive role on the switching speed, the optimal concentration being around 25%;
- Experimental work revealed that silver doping leads to an increase in the activation energy of crystallization.