Banca de QUALIFICAÇÃO: JOÃO HENRIQUE QUINTINO PALHARES
Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.DISCENTE : JOÃO HENRIQUE QUINTINO PALHARES
DATA : 17/02/2020
HORA: 14:00
LOCAL: sala 306, 3º andar, Bloco B, Campus SA da Fundação Universidade Federal do ABC, localizada na Avenida dos Estados, 5001, Santa Terezinha, Santo André, SP
TÍTULO:
Effect of doping in tantalum oxide-based resistive switching devices (Memristors)
PÁGINAS: 42
RESUMO:
The scaling limit of silicon-based memory devices has been challenging researchers to find a new technology for store and process computational information. Resistive switching devices based on ionic carriers have attracted attention due to their simple structure (only two electrodes), low energy consumption, high scalability, endurance and ability to promote novel computing architectures. Resistive switching is a physical phenomenon that is basically the change of the resistance state of a dielectric thin layer induced by high electric field. For oxide-based valence-change memories, also known as memristors, oxygen vacancies are the main responsible for the resistive switching phenomenon. Researchers worldwide are trying to find and understand different ways to promote oxygen vacancy formation in oxides. The proposal of this work is to evaluate methods for the doping, intrinsic or extrinsic, of tantalum oxide films produced by pulsed laser deposition (PLD). Intrinsic doping occurs whenever the compound stoichiometry ratio deviates (oxygen deficiency) and it can be achieved by controlling parameters such as the oxygen partial pressure during the film growth. Extrinsic doping occurs when a foreign atom is added to the compound aiming to change the vacancy content and mobility. As there are few works studying tantalum oxide devices prepared by PLD, the idea of this work is to understand the difference and the implications of both doping methods using device performance. A pure tantalum oxide target and a mixed one using 20% ZrO2 and 80% Ta2O5 were prepared and used to deposit the resistive switching active layers by PLD using a 248 nm a KrF excimer laser. The thin films composition, stoichiometry and oxidation state distributions were determined by x-ray photoelectron spectroscopy (XPS). Thin film thickness, roughness and optical properties were investigated by atomic force microscopy (AFM), ellipsometry spectroscopy (ES) and scanning electron microscopy (SEM). Electrical parametrization was done using a Keysight B1500A semiconductor device parameter analyzer. Ron Roff ratio (Resistance window), set, reset voltages, forming voltage and synaptic behavior were the performance metrics used to compare devices. Intrinsically doped devices presented values of set and reset voltages of 4 V, forming voltage of 6 V, Ron Roff ratio of 1.57. On the other hand, extrinsically doped devices presented values of set and reset voltages of 2 V, Ron Roff Ratio of 4 and they are forming-free.
MEMBROS DA BANCA:
Presidente - Interno ao Programa - 1544408 - GUSTAVO MARTINI DALPIAN
Membro Titular - Examinador(a) Interno ao Programa - 2604128 - ALEXANDRE JOSE DE CASTRO LANFREDI
Membro Titular - Examinador(a) Externo ao Programa - 1073241 - MARINA SPARVOLI DE MEDEIROS
Membro Titular - Examinador(a) Externo à Instituição - EVERTON BONTURIM - UPM