مشخصات پژوهش

A novel functional field effect transistor (FET) is introduced. The proposed FET is modeledon graphene nanoribbon (GNR), however it is applicable for any two dimensional structureswith energy gap. As in most graphene-based FETs, the current passes through semiconducting 2D GNR [1-6]. But here by the special geometry of gate contacts, the GNR is turned into two coupled quantum dots in series. Applications of quantum dots (QD) in electronic and optoelectronic devices, such as FETs, rest beside the discrete energy levels of QD [1,2, 7-10]. At the modeled structure, the two coupled QDs are achieved by just one gate electrode voltage in the way that the gate metal is not directly attached to the dielectric layer on top of the channel region, but two separate metallic plates on top of dielectric layer cover the channel region. Then, a single metallic gate electrode is laid on top of two metallic plates. In this structure, the single gate electrode is equipotential with the plates and turn them into separate gate electrodes with equal voltage. Also, the gate plates don’t cover the channel region at the two ends of channel where it is connected to the highly doped source and drain regions. This means that there are two thin layers at the two ends of channel region, that are not under the gate control and so act as barriers. By applying gate voltage, discrete energy levels are generated in the two quantum dots of the channel. Coupling between QDs and matching the corresponding energy levels are responsible for resonant tunneling through the discrete energy levels. So, the coupling strength of dots and the sizes of dots determine the current characteristic of the device. By solving the NEGF and 3D Poisson equations self consistently, current of the FET is derived [11, 12]. As in other QD-based nanoelectronic devices, our modeled FET exhibits resonant tunneling of carries via discrete energy levels of two QDs and the resulting negative differential resistance (NDR) has wide ap