van der Waals Bonded Co/h-BN Contacts to Ultrathin Black Phosphorus Devices

Abstract

Due to the chemical inertness of 2D hexagonal-Boron Nitride (h-BN), few atomic-layer h-BN is often used to encapsulate air-sensitive 2D crystals such as Black Phosphorus (BP). However, the effects of h-BN on Schottky barrier height, doping and contact resistance are not well known. Here, we investigate these effects by fabricating h-BN encapsulated BP transistors with cobalt (Co) contacts. In sharp contrast to directly Co contacted p-type BP devices, we observe strong n-type conduction upon insertion of the h-BN at the Co/BP interface. First principles calculations show that this difference arises from the much larger interface dipole at the Co/h-BN interface compared to the Co/BP interface, which reduces the work function of the Co/h-BN contact. The Co/h-BN contacts exhibit low contact resistances (~ 4.5 k-ohm), and are Schottky barrier free. This allows us to probe high electron mobilities (4,200 cm2/Vs) and observe insulator-metal transitions even under two-terminal measurement geometry.

References in corpus (11)

• Boron nitride substrates for high-quality graphene electronics
• High Electron Mobility, Quantum Hall Effect and Anomalous Optical Response in Atomically Thin InSe
• Black Phosphorus-Monolayer MoS2 van der Waals Heterojunction P-N Diode
• Accessing the transport properties of pristine few-layer black phosphorus by van der Waals passivation in inert atmosphere
• Electrical characterization of fully encapsulated ultra thin black phosphorus-based heterostructures with graphene contacts
• Device Perspective for Black Phosphorus Field-Effect Transistors: Contact Resistance, Ambipolar and Scaling
• Electron and Hole Mobilities in Single-Layer WSe2
• Controlling the Schottky barrier at MoS2|metal contacts by inserting a BN monolayer
• Low Resistance Metal Contacts to MoS2 Devices with Nickel-Etched-Graphene Electrodes
• Ambipolar Insulator-to-Metal Transition in Black Phosphorus by Ionic-Liquid Gating
• Gate-tunable black phosphorus spin valve with nanosecond spin lifetimes

Cited by in corpus (2)

• Giant proximity exchange and valley splitting in transition metal dichalcogenide/$h\mathrm{BN}$/(Co, Ni) heterostructures
• Carrier Drift Control of Spin Currents in Graphene-Based Spin-Current Demultiplexers