Band Alignment in Black Phosphorus/Transition Metal Dichalcogenide Heterolayers: Impact of Charge Redistribution, Electric Field, Strain and Layer Engineering

TL;DR

This study uses DFT simulations to explore how charge redistribution, electric fields, strain, and layer engineering can tune the band alignment in BP/TMD heterostructures, enabling customizable electronic and optoelectronic device functionalities.

Contribution

It demonstrates the tunability of band alignment in BP/MoS2 heterostructures through external stimuli and layer engineering, revealing potential for reconfigurable electronic devices.

Findings

Charge redistribution shifts band alignment from Electron Affinity Rule predictions.

External electric fields, strain, and layer number enable transition between Type I, II, and III heterostructures.

Different TMDs with BP exhibit various band alignment types, broadening application possibilities.

Abstract

The objective of this work is to study the effects of charge redistribution, applied layer-normal electric fields, applied strain, and layer engineering on the band alignment of Black Phosphorus (BP)/Molybdenum disulphide (MoS2) heterostructure through Density Functional Theory (DFT) simulations. Black phosphorus works as a p-type material with high mobility, mechanical flexibility, and sensitivity to number of layers. Combining it with the more electronegative material, MoS2 results in strong carrier confinement and a Type II heterostructure. Charge redistribution among the layers shifts the band alignment expected from the Electron Affinity Rule. Applied external fields, strain and multiple BP layers provide band-alignment tunability within the Type II range and/or, transition to Type I and Type III heterostructures. The tunability in BP/MoS2 heterostructure may be useful as tunnel field effect transistors, rectifier diodes with tunable barrier height, reconfigurable FETs, and electro-optical modulators. Furthermore, considering heterostructures of monolayer BP with other monolayer Transitional Metal Dichalcogenides (TMD) suggests the ability to achieve different band alignment types. In our simulations, a Type I alignment is found with Tungsten diselenide (WSe2), Molybdenum diselenide (MoSe2), and Tungsten disulphide (WS2), and a Type III for Hafnium disulphide (HfS2) and Hafnium diselenide (HfSe2).