Modulating Charge Separation with Hexagonal Boron Nitride Mediation in Vertical Van der Waals Heterostructures
Journal
ACS Applied Materials and Interfaces
Journal Volume
12
Journal Issue
23
Pages
26213-26221
Date Issued
2020
Author(s)
Paul Inbaraj, C.R.
Abstract
Tuning the optical and electrical properties by stacking different layers of two-dimensional (2D) materials enables us to create unusual physical phenomena. Here, we demonstrate an alternative approach to enhance charge separation and alter physical properties in van der Waals heterojunctions with type-II band alignment by using thin dielectric spacers. To illustrate our working principle, we implement a hexagonal boron nitride (h-BN) sieve layer in between an InSe/GeS heterojunction. The optical transitions at the junctions studied by photoluminescence and the ultrafast pump-probe technique show quenching of emission without h-BN layers exhibiting an indirect recombination process. This quenching effect due to strong interlayer coupling was confirmed with Raman spectroscopic studies. In contrast, h-BN layers in between InSe and GeS show strong enhancement in emission, giving another degree of freedom to tune the heterojunction property. The two-terminal photoresponse study supports the argument by showing a large photocurrent density for an InSe/h-BN/GeS device by avoiding interlayer charge recombination. The enhanced charge separation with h-BN mediation manifests a photoresponsivity and detectivity of 9 × 102 A W-1 and 3.4 × 1014 Jones, respectively. Moreover, a photogain of 1.7 × 103 shows a high detection of electrons for the incident photons. Interestingly, the photovoltaic short-circuit current is switched from positive to negative, whereas the open-circuit voltage changes from negative to positive. Our proposed enhancement of charge separation with 2D-insulator mediation, therefore, provides a useful route to manipulate the physical properties of heterostructures and for the future development of high-performance optoelectronic devices. Copyright © 2020 American Chemical Society.
Subjects
carrier separation; insulator mediation; monochalcogenide; photodetector; van der Waals heterostructure
SDGs
Other Subjects
Degrees of freedom (mechanics); Germanium compounds; Heterojunctions; III-V semiconductors; Nitrides; Open circuit voltage; Optoelectronic devices; Quenching; Selenium compounds; Semiconductor quantum wells; Separation; Spectroscopic analysis; Van der Waals forces; Charge recombinations; Hexagonal boron nitride; Hexagonal boron nitride (h-BN); Optical and electrical properties; Quenching of emission; Raman spectroscopic study; Recombination process; Type II band alignments; Boron nitride; article; electron; photoluminescence; photon; Raman spectrometry; short circuit current
Type
journal article