Spin transport In graphene ferromagnet-semiconductor devices and magneto-transport properties of four-layer graphene structure

• Main Author: Azat Sulaev
• Other Authors: Lew Wen Siang
• Format: Final Year Project
• Language: English
• Published: 2011
• Subjects: DRNTU::Science::Physics::Electricity and magnetism
• Online Access: http://hdl.handle.net/10356/45685
• Institution: Nanyang Technological University

Most of the modern day Field-Effect Transistors (FET) in microelectronics are constructed in order to operate on the transport of charges. Devices with tunneling magnetoresistance and giant magnetoresistance effects in ferromagnetic-layer structures have already exploited in the industry. They carry one of the most important tasks in the electronics as switches, they determine the speed and the size of the corresponding processors and integrated circuits. Developing technology in the future will demand devices smaller in size, robust and more versatile. New spin-FET devices have shown promising properties for future electronics. Spin-FET devices utilize spin of the charge as an information carrier. They are still on the early stage of development and many transport properties of the spintronic devices are yet to be studied. To be able to exploit the spin properties of the electrons specific design of the device and suitable materials are must be chosen. Material for the spintronic device was chosen to be graphene, because this material shows one of the best spin properties at room and low temperatures. Besides spintronics graphene could be exploited in many areas of the semicounductor technology or photonics and seen as potential replacement for the Silicon. Because it has shown higher electron mobility, stable and can be utilized as a building block for different structures. Graphene is semimetal and zero-gap semiconductor by its nature. Another interesting property of the graphene is the tunable band gap that could be induced by external magnetic or electric field. In the conventional semiconductors bandgap is fixed by the crystalline structure. This makes graphene very unique semiconductor material for the future technologies. Other properties that makes graphene very convenient material for the devices is high mechanical strength, because by 2009 graphene was tested to have the highest mechanical strength, 200 times higher than steel.55 Also melting point is as high as 3600 K and graphene is stable at temperatures up to 500°C, and inert to most of the gases.56 For the nanotechnology that requires fabrication of the low dimensional devices graphene is suitable material, because graphene fabrication doesn’t require complicated technology and monolayer graphene, whose thickness is in the dimensions of the atom, could be fabricated mechanically.