Electrochemically Prepared Graphene Field Effect Transistors and Magnetoresistive Devices.

摘要

Electrochemical deposition is a class of techniques used to deposit coatings onto conductive substrates that are relevant to everyday products such as integrated circuits, magnetic recording devices, and multilayer structures. This dissertation will discuss the use of electrochemical depositions to fabrication nano/microelectronic devices.;Chapter 1 demonstrates the electrodeposition of pinhole free, low-k dielectric thin films on graphene, and the use of these films a dielectric for graphene field effect transistors (FET). The electro-oxidation of phenolic compounds were shown to form ultrathin (∼3-4 nm) insulating polymers on the surface of mechanically exfoliated graphene. The performance of these top-gated FET devices, which were successfully gated through the polymer with low leakage currents, will be discussed. These insulating phenolic polymers were also shown to assist the growth of hafnium oxide deposited by ALD to form higher dielectric films.;Chapters 2 and 3 discuss the electrodeposition of bismuth and manganese-bismuth alloys respectively. Bismuth was electrodeposited on ferromagnetic nanojunctions to create spin valve devices. The magnetoresistance of the devices exhibited a parabolic resistance response to a magnetic field, typical for bismuth, with an additional small negative magnetoresistance (0.1%). Manganese-bismuth, a ferromagnetic metal with a high coercivity, was prepared by electrodeposition for the first time. The films were prepared with single and dual bath depositions from various metal ion containing solutions. The films prepared from the dual bath depositions exhibited large coercivities (>2.5 kOe) after being annealed at 269°C.