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PhD Defence : Benjamin RAMOS

par Agnès Gaunie Picart - publié le

Study of a ferroelectric material for organic transistor applications : Influence on the electrical performances
Tuesday 5 th december 10 : 30 AM
Amphithéatre Concorde (Université Paul Sabatier site)
Jury :
Mme Christine VIDELOT ACKERMANN, Chargé de Recherche à l’Université Aix-Marseille (Rapporteur)
M. Kamal LMIMOUNI, Professeur à l’Université de Lille (Rapporteur)
M. Fabien PASCAL, Professeur à l’Université de Montpellier (Examinateur)
M. Jean-Pascal CAMBRONNE, Professeur à l’Université de Toulouse Paul Sabatier (Examinateur)
M. Marc TERNISIEN, Maître de Conférences à l’Université Paul Sabatier (Directeur de thèse)
M. David BUSO, Maître de Conférences à l’Université Paul Sabatier (Co-directeur de thèse)

Abstract :

This thesis deals with the study of a ferroelectric material as gate dielectric for organic transistor applications. The configuration adopted is bottom-gate top-contact. The semiconductor used is an electron transport material. In a first part, we made organic field effect transistors (OFETs) with a layer of PMMA as a gate dielectric. This material, very studied and well known, serves as reference. We also carried out a study on the channel length, the organic semiconductor deposition rate and the dielectric thickness, in order to deduce the impact of these parameters on OFETs performances. After optimization, we have demonstrated an improvement of the mobility, on/off current ratio, capacitance and a reduction of supply and threshold voltages. These results have been interpreted using electrical characterizations. In a second step, the poly (vinylidenefluoride-co-trifluoroethylene) (P (VDF-TrFE)) ferroelectric material was added to provide a hybrid dielectric with PMMA. This OFET combine the advantages of high permittivity of P(VDF-TrFE) and low roughness of PMMA. A comparative study was carried out with reference transistors. For same dielectric thickness, a reduction of the supply and threshold voltages and an improvement of the mobility is obtained for the OFET implementing ferroelectric material. The discussion of these results is supported by electrical and morphological characterizations.