Dual-mode operation of 2D material-base hot electron transistors

Abstract

Vertical hot electron transistors incorporating atomically-thin 2D materials, such as graphene or MoS2, in the base region have been proposed and demonstrated in the development of electronic and optoelectronic applications. To the best of our knowledge, all previous 2D material-base hot electron transistors only considered applying a positive collector-base potential (VCB > 0) as is necessary for the typical unipolar hot-electron transistor behavior. Here we demonstrate a novel functionality, specifically a dual-mode operation, in our 2D material-base hot electron transistors (e.g. with either graphene or MoS2 in the base region) with the application of a negative collector-base potential (VCB < 0). That is, our 2D material-base hot electron transistors can operate in either a hot-electron or a reverse-current dominating mode depending upon the particular polarity of VCB. Furthermore, these devices operate at room temperature and their current gains can be dynamically tuned by varying VCB. We anticipate our multi-functional dual-mode transistors will pave the way towards the realization of novel flexible 2D material-based high-density and low-energy hot-carrier electronic applications.

High Performance Amplifier Element Realization via MoS2/GaTe Heterostructures

“…There is considerable freedom in integrating 2DLMs and various nanoscale materials to create a set of diverse van der Waals heterostructures (vdWHs), with functions that could not be achieved previously. Until now, in addition to basic circuit elements such as transistors and CMOSs16, 17, 18, 19 based on mechanically exfoliated 2DLMs, more complex circuits have also been achieved recently that were based on vdWHs,20, 21, 22, 23, 24 such as memories, detectors, and sensors. Nevertheless, as an important part of integrated circuits, 2DLM‐based amplifier circuits have rarely been studied.…”

Hot Electron Transistor with van der Waals Base-Collector Heterojunction and High-Performance GaN Emitter

“…Apart from this fact, forming ultrathin layers of the dielectrics on a graphene base is very challenging because the chemically inert, hydrophobic surface of graphene does not allow conformal nucleation of atomic layer deposition (ALD) thin film oxides . Therefore, as a result, relatively thick layers of oxides (∼15–55 nm) ,,, have been used so far to achieve conformal, pinhole free barriers. Beside their thickness, these dielectrics have relatively large conduction band offsets with graphene (3.3 eV for Al 2 O 3 and 2 eV for HfO 2 ), which cause a dramatic decrease of the current tunneling probability through the barrier and, thus, α BC becomes very poor.…”

Approaching the Collection Limit in Hot Electron Transistors with Ambipolar Hot Carrier Transport

“…Hot electron transistor (HET) is a promising device concept possessing an ultrashort channel less than the mean-free-path (MFP) of carriers. The emergence of two-dimensional (2D) materials makes it possible to further scale down the channel length to the single atomic layer limit. − Given the high kinetic energy carriers in the ultrashort channel, HET is promising for high-speed applications ,− and provides a superior platform to study the nonequilibrium hot carrier dynamics. − One of the ultimate goals in the development of HET is to obtain 100% collection efficiency, which is vital for realizing devices with high current gain and studying hot carrier dynamics. To obtain high collection efficiency, graphene (Gr) has been proposed as an excellent base material in HET owing to its atomically thin body and high electrical conductivity. ,, With the development of van der Waals (vdW) integration technique − and induction of 2D materials, the quality of interfaces in HET has been largely improved owing to their dangling-bond-free surfaces and atomically sharp interfaces, but these hybrid structures still suffer hot carrier loss due to the nonideal interfaces between 2D and three-dimensional (3D) materials.…”