Banca de DEFESA: JOÃO HENRIQUE QUINTINO PALHARES

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : JOÃO HENRIQUE QUINTINO PALHARES
DATA : 14/08/2020
HORA: 09:30
LOCAL: Santo André
TÍTULO:

Effect of doping in tantalum oxide-based resistive switching devices (Memristors)

PÁGINAS: 60
RESUMO:

Resistive switching (RS) devices (memristors) based on ionic carriers have attracted attention due to their simple structure (only two terminals), low energy consumption, high scalability, endurance, and possibility of novel computing architectures. However, variability is still a limiting factor for RS applications. In oxide-based RS devices, the reversible change (switching) in the resistance of a thin dielectric layer results from movement of oxygen vacancies induced by high electric fields. To reduce variability, better understating and control of oxygen vacancy formation and movement is paramount. In this work, the intrinsic and extrinsic doping of tantalum oxide layers in RS devices was investigated. Pure and Zr-doped tantalum oxide thin films were prepared by pulsed laser deposition (PLD) and characterized by atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS), and spectroscopic ellipsometry (SE) to evaluate surface morphology, film thickness, stoichiometry, electronic structure, and presence of defects.  The pure and Zr-doped films were amorphous and had smooth surface. SE reveals that Zr addition promotes a sub-gap optical absorption that can be associated with increased concentration of oxygen vacancies. In pure tantalum oxide films, a similar effect can be achieved by reducing the oxygen partial pressure during deposition. RS devices were micropatterned by photolithography using dog-bone and common bot contact architectures. The device response was analyzed using an electronic hopping transport model that enables determination of defect (trap) concentration, which should be proportional to the O vacancy concentration. Such analysis confirms the SE results that that Zr doping promotes O vacancy formation. Systematic electrical parametrization shows that Zr-doped devices are more reliable, have a higher resistance window, higher yield, and lower forming voltage, which might be ascribed to doping effects on filament confinement and oxygen vacancy formation. This study suggests that Zr doping of tantalum oxide memristor is a promising vacancy engineering strategy to tune memristor performance.

MEMBROS DA BANCA:
Presidente - Interno ao Programa - 1552290 - ANDRE SANTAROSA FERLAUTO
Membro Titular - Examinador(a) Interno ao Programa - 2604128 - ALEXANDRE JOSE DE CASTRO LANFREDI
Membro Titular - Examinador(a) Externo ao Programa - 364.742.988-04 - EVERTON BONTURIM - UPM
Membro Suplente - Examinador(a) Interno ao Programa - 1544408 - GUSTAVO MARTINI DALPIAN
Membro Suplente - Examinador(a) Externo à Instituição - RODRIGO GRIBEL LACERDA