Self-Powered and Broadband Bismuth Oxyselenide/p-Silicon Heterojunction Photodetectors with Low Dark Current and Fast Response

Self-Powered and Broadband Photodetectors Based on High-performance Mixed Dimensional Sb2O3/PdTe2/Si Heterojunction for Multiplex Environmental Monitoring

Solar-blind ultraviolet (SBUV) to near-infrared (NIR) broadband photodetectors (BB-PD) have important applications in environmental monitoring and other applications. However, it is challenging to prepare SBUV-IR photosensitive materials via simple steps and to construct SBUV-IR broadband devices for multiplex detection with high sensitivity at different wavelengths. Here, self-powered and broadband photodetectors using a high-performance mixed dimensional Sb2O3 nanorod 1-dimension (1D)/monodisperse microdiamond-like PdTe2 3-dimension (3D)/Si (3D) heterojunction for multiplex detection of environmental pollutants with high sensitivity at broadband wavelength are developed. The 1D/3D mixed dimensional Sb2O3/PdTe2/Si structure combines the advantages of strong light absorption, high carrier transport efficiency of 1D Sb2O3 nanorods, and expansion of interface barrier caused by 3D microdiamond-like PdTe2 interlayer to improve the photocurrent density and self-powered ability. The efficient photogenerated charge separation enables anon/off ratio of more than 5 × 106. The device exhibits excellent photoelectric properties from 255 to 980 nm with the responsivity from 4.56 × 10-2 to 6.55 × 10-1 AW-1, the detectivity from 2.36 × 1012 to 3.39 × 1013 Jones, and the sensitivity from 3.90 × 107 to 1.10 × 1010 cm2 W-1 without external bias. Finally, the proposed device is applied for the multiplex monitoring of environmental pollution gases NO2 with the detection limit of 200 ppb and PM2.5 particles at mild pollution at broadband wavelength. The proposed BB-PD has great potential for multiplex detection of environmental pollutants and other analytes at broadband wavelength.

Efficient Carrier Transport in 2D Bi2O2Se/CsBi3I10 Perovskite Heterojunction Enables Highly-Sensitive Broadband Photodetection

2D Bi2O2Se has recently garnered significant attention in the electronics and optoelectronics fields due to its remarkable photosensitivity, broad spectral absorption, and excellent long-term environmental stability. However, the development of integrated Bi2O2Se photodetector with high performance and low-power consumption is limited by material synthesis method and the inherent high carrier concentration of Bi2O2Se. Here, a type-I heterojunction is presented, comprising 2D Bi2O2Se and lead-free bismuth perovskite CsBi3I10, for fast response and broadband detection. Through effective charge transfer and strong coupling effect at the interfaces of Bi2O2Se and CsBi3I10, the response time is accelerated to 4.1 µs, and the detection range is expanded from ultraviolet to near-infrared spectral regions (365-1500 nm). The as-fabricated photodetector exhibits a responsivity of 48.63 AW-1 and a detectivity of 1.22×1012 Jones at 808 nm. Moreover, efficient modulation of the dominant photocurrent generation mechanism from photoconductive to photogating effect leads to sensitive response exceeding 103 AW-1 for heterojunction-based photo field effect transistor (photo-FETs). Utilizing the large-scale growth of both Bi2O2Se and CsBi3I10, the as-fabricated integrated photodetector array demonstrates outstanding homogeneity and stability of photo-response performance. The proposed 2D Bi2O2Se/CsBi3I10 perovskite heterojunction holds promising prospects for the future-generation photodetector arrays and integrated optoelectronic systems.

Direct growth Bi2O2Se nanosheets on SiO2/Si substrate for high-performance and broadband photodetector

Bi2O2Se, a newly emerging two-dimensional (2D) material, has attracted significant attention as a promising candidate for optoelectronics applications due to its exceptional air stability and high mobility. Generally, mica and SrTiO3substrates with lattice matching are commonly used for the growth of high-quality 2D Bi2O2Se. Although 2D Bi2O2Se grown on these insulating substrates can be transferred onto Si substrate to ensure compatibility with silicon-based semiconductor processes, this inevitably introduces defects and surface states that significantly compromise the performance of optoelectronic devices. Herein we employ Bi2Se3as the evaporation source and oxygen reaction to directly grow Bi2O2Se nanosheets on Si substrate through a conventional chemical vapor deposition method. The photodetector based on the Bi2O2Se nanosheets on Si substrate demonstrates outstanding optoelectronics performance with a responsivity of 379 A W-1, detectivity of 2.9 × 1010Jones, and rapid response time of 0.28 ms, respectively, with 532 nm illumination. Moreover, it also exhibits a broadband photodetection capability across the visible to near-infrared range (532-1300 nm). These results suggest that the promising potential of Bi2O2Se nanosheets for high-performance and broadband photodetector applications.

Electric Control of Helicity-Dependent Photocurrent and Surface Polarity Detection on Two-Dimensional Bi2O2Se Nanosheets

Bismuth oxyselenide (Bi2O2Se) is a two-dimensional (2D) layered semiconductor material with high electron Hall mobility and excellent environmental stability as well as strong spin-orbit interaction (SOI), which has attracted intense attention for application in spintronic and spin optoelectronic devices. However, a comprehensive study of spin photocurrent and its microscopic origin in Bi2O2Se is still missing. Here, the helicity-dependent photocurrent (HDPC) was investigated in Bi2O2Se nanosheets. By analyzing the dependence of HDPC on the angle of incidence, we find that the HDPC originates from surface states with Cs symmetry in Bi2O2Se, which can be attributed to the circular photogalvanic effect (CPGE) and circular photon drag effect (CPDE). It is revealed that the HDPC current almost changes linearly with the source-drain voltage. Furthermore, we demonstrate effective tuning of HDPC in Bi2O2Se by ionic liquid gating, indicating that the spin splitting of the surface electronic structure is effectively tuned. By analyzing the gate voltage dependence of HDPC, we can unambiguously identify the surface polarity and the surface electronic structure of Bi2O2Se. The large HDPC in Bi2O2Se nanosheets and its efficient electrical tuning demonstrate that 2D Bi2O2Se nanosheets may provide a good platform for opto-spintronics devices.