Modulation of Quantum Tunneling via a Vertical Two-Dimensional Black Phosphorus and Molybdenum Disulfide p–n Junction

Abstract

Diverse diode characteristics were observed in two-dimensional (2D) black phosphorus (BP) and molybdenum disulfide (MoS) heterojunctions. The characteristics of a backward rectifying diode, a Zener diode, and a forward rectifying diode were obtained from the heterojunction through thickness modulation of the BP flake or back gate modulation. Moreover, a tunnel diode with a precursor to negative differential resistance can be realized by applying dual gating with a solid polymer electrolyte layer as a top gate dielectric material. Interestingly, a steep subthreshold swing of 55 mV/dec was achieved in a top-gated 2D BP-MoS junction. Our simple device architecture and chemical doping-free processing guaranteed the device quality. This work helps us understand the fundamentals of tunneling in 2D semiconductor heterostructures and shows great potential in future applications in integrated low-power circuits.

Gate-Tunable WSe2/SnSe2 Backward Diode with Ultrahigh-Reverse Rectification Ratio

“…In this work, we exploit this property of the WSe2/SnSe2 heterojunction to demonstrate a backward diode with a large curvature coefficient of ~37 V -1 , coupled with an extremely high reverse rectification ratio of ~2.1 × 10 4 , outperforming previously reported numbers 19,20,[33][34][35][36][37][38][39][40][41][42][43] . We also demonstrate an efficient modulation of the rectification ratio by tuning the applied gate voltage, contact metals, and thickness of the WSe2 layer.…”

“…Backward diode 1,[19][20][21] is a special type of diode that conducts more efficiently in the reverse direction than in the forward direction, typically due to strong Zener tunneling under reverse bias.…”

Independent Band Modulation in 2D van der Waals Heterostructures via a Novel Device Architecture

“…However, due to the absence of a bandgap, graphene‐based TFETs are unable to obtain a high on/off ratio of the current. TMD‐based TFET devices have also been experimentally demonstrated, including MoS 2 /WSe 2 ,24, 32, 33 MoS 2 /BP,34, 35 SnSe 2 /BP,36 SnSe 2 /WSe 2 ,37 and ReS 2 /BP 35. In these devices, gate‐tunable tunneling current governed by the band‐to‐band tunneling (BTBT) mechanism can be observed through electrostatic gating of energy‐band alignment and carrier density under specific device architectures.…”

“…In order to suppress the series resistance, recently, another self‐align method is proposed to fabricate short‐channel vdWs heterostructure device 38. It is also inefficient to modulate the band offset unless a more complicated architecture is used (e.g., dual‐gate structure24) or the gate‐control capability is drastically enhanced (e.g., by applying a thin, high‐k dielectric24 or ionic electrolyte34, 39). Moreover, in a vertically stacked 2DLM heterostructure, the energy‐band offset is mainly determined by the potential drop across the vdWs gap at the interface within the overlap region, and is difficult to be modulated directly by gate electrical field due to the screening effect associated with this vertically stacked structure.…”

Multilayer Black Phosphorus Near-Infrared Photodetectors

“…Thus, band diagrams for BP nanoflakes with different thickness are shown in Figure 3f. All the positions of the Fermi levels were extracted from Liu’s group [12]. For thickness less than screening length (~10 nm), the device exhibits bipolar operation [5].…”