Low-voltage MoS2 based heterojunction tunnel field-effect transistors and Dirac-source diode

Abstract

Level of integration in integrated circuit to extend Moore’s law reaches the limit. So, to extend Moore’s law, low power circuit technology is needed. In this thesis, by taking advantage of the fact that the work functions of graphene and graphite are different, the diode characteristics were observed in a device using graphene and graphite as electrodes on both sides of MoS$_2$. In particular, the device operates as a Dirac-source Schottky diode, in which the current rapidly increases according to the bias voltage by using the drastic change in the electron carrier density from the linear band structure of graphene. Additionally, in same device, we found that our Dirac-source triode works as a DS-FET. Limitations of integrated circuits, the performance of transistors as well as diodes must overcome the limitations of conventional MOSFETs. Several researches have been proposed to overcome this problem, but the tunnel field-effect transistors (TFETs) is the most promising among them. In this thesis, a heterojunction TFET was studied using monolayer MoS$_2$, which is a two-dimensional n-type semiconductor material, and bulk black phosphorus and WSe$_2$, which are two-dimensional p-type semiconductor materials.