Ultrasensitive Photoresponsive Devices Based on Graphene/BiI₃ van der Waals Epitaxial Heterostructures

Abstract

In recent years, bismuth iodide (BiI 3 ), a layered metal halide semiconducting light absorber with a wide bandgap of ≈1.8 eV and strong optical absorption in the visible region, has received greater attention for photovoltaic applications. In this study, ultrasensitive visible-light photodetectors with graphene/ BiI 3 vertical heterostructures are achieved by van der Waals epitaxies. The BiI 3 films deposited on graphene show flatter morphologies and significantly better crystallinities than that of BiI 3 films on SiO 2 substrates, mainly due to weak van der Waals interactions at the graphene/BiI 3 interface. Hybrid photodetectors with highly crystalline graphene/BiI 3 heterostructures demonstrate an ultrahigh responsivity of 6 × 10 6 A W −1 , shot-noise-limited detectivity of 7 × 10 14 Jones, and a relatively short response time of ≈8 ms. Compared to most previously reported graphene-based hybrid photodetectors, these devices have comparable photosensitivities but a faster response speed and lower operation voltage, which is quite promising for ultralow intensity visible-light sensors. Moreover, the electronic structure and interfacial chemistry at the graphene/BiI 3 heterojunctions are investigated using photoemission spectroscopy. The results give clear evidence that no chemical interactions occur between graphene and BiI 3 , resulting in the van der Waals epitaxial growth, and the measured band bending consistently illustrates that a photoinduced charge transfer occurs at the graphene/BiI 3 interface.

Symmetry‐Reduction Enhanced Polarization‐Sensitive Photodetection in Core–Shell SbI3/Sb2O3 van der Waals Heterostructure

“…Group V-VI compounds (Sb, Bi/S, Se, Te) [33][34][35][36] and Group V-VII compounds (As, Sb, Bi/Cl, Br, I) of the nanowires have been investigated in photovoltaic materials [37] and they could be synthesized by chemical vapor transport (CVT) or chemical vapor deposition (CVD). Comparable photoresponse of WSe 2 /BiI 3 [38] and graphene/BiI 3 [39] van der Waals heterostructures have been demonstrated. Previous theoretical studies showed that group V trihalides had suitable bandgap, tunable bandedge and moderated mobility.…”

Forming‐Free, Nonvolatile, and Flexible Resistive Random‐Access Memory Using Bismuth Iodide/van der Waals Materials Heterostructures

“…Similar to the case of BiI 3 on the graphene/SiO 2 substrate, for the Si and graphene/copper substrates, four peaks were located at 13.12°, 26.05°, 39.33°, and 53.19°, corresponding to the (00l) family planes of the BiI 3 structure. [38] However, the XRD peaks of BiI 3 on the graphene/copper substrate were obviously much higher than those of BiI 3 on the bare silicon substrate. [38] This could be because the BiI 3 crystals were well-orientated to the c-axis, thereby resulting in a much higher diffraction intensity of X-rays.…”

“…[38] However, the XRD peaks of BiI 3 on the graphene/copper substrate were obviously much higher than those of BiI 3 on the bare silicon substrate. [38] This could be because the BiI 3 crystals were well-orientated to the c-axis, thereby resulting in a much higher diffraction intensity of X-rays. This is consistent with the SEM results.…”

“…[1][2][3] Currently, the development of traditional memory cannot follow Moore's law; therefore, that used (CH 3 NH 3 ) 3 Sb 2 Br 9 as an insulator, exploiting the selfformation of the metal Sb filament, to obtain an on/off ratio of ≈100 and a retention of 10 4 s. [14] Of 2D materials and of precursors of bismuth-related perovskite, BiI 3 , which has a high absorption coefficient in the visible region and which is composed of heavy atoms, has been considered a promising material in the field of photovoltaics, photodetection, and gamma-ray sensing. [32][33][34][35][36][37][38][39] Each layer of the BiI 3 structure consists of the I-Bi-I ionic bonding, and the interlayer is stacked by van der Waals forces. In this study, to investigate the resistive-switching property and the flexibility of BiI 3 , we fabricated an RRAM by using the simple structure of Au/ BiI 3 /van der Waals materials/copper foil.…”

Photoinduced charge carrier dynamics in a ZnSe quantum dot-attached CdTe system

“…Because of numerous potential applications and diverse novel characteristics, much attention is currently given to fabricating and classifying nanomaterials with various morphologies [1]. In the past, nanomaterials of many shapes have been designed for various types of photoresponsive devices [2][3][4][5]. Nanomaterials, particularly one-dimensional nanostructures, have novel features and a wide-ranging scope for nano-device fabrication [6,7].…”