Abnormal low-temperature behavior of a continuous photocurrent in Bi2S3 nanowires

Abstract

High-quality Bi 2 S 3 nanowires are synthesized and their photoresponses are investigated in detail. Our results show that the photoresponsive curves have distinctly different characteristics at low-temperature (50 K) compared to those at room temperature (290 K). The transferred-electron effect is believed to cause this difference. A first principle calculation shows that Bi 2 S 3 has many energy valleys, which agree with our experimental analysis. At low temperature, due to the lack of sufficient phonon energy, the photoexcited electrons in Bi 2 S 3 mainly aggregate at the bottom of the conduction band. When this electron concentration increased to a high enough level after illumination, an electron transfer between the energy valleys happened and the photocurrent began to decrease slowly after the rapid increase in the first stage. After the transfer process reaches equilibrium, the photocurrent reaches a minimum, thus the trap states play a dominant role and the photocurrent rises slowly again. Furthermore, photocurrent curves at different temperatures were recorded to estimate the phonon energy value needed to assist the electron transitions. The required phonon energy is calculated to be about 16.3 meV (corresponding to 190 K), which fits well with previous results. Experimental detailsBi 2 S 3 nanowires (NWs) were synthesized by a solvothermal process following the literature: 17 57.09 mg thiourea, 157.67 mg anhydrous bismuth chloride, and 1 g polyvinylpyrrolidone (PVP)

Low‐Noise Dual‐Band Polarimetric Image Sensor Based on 1D Bi2S3 Nanowire

“…[ 29 ] The traditional Raman spectrum (Figure S3f , Supporting Information) under laser (785 nm) shows distinct Raman peaks at 56, 73, 102, 188, 240, and 265 cm −1 are all consistent with the previous studies. [ 25 , 30 ] In addition, X‐ray photoelectron spectroscopic (XPS) measurement is further performed to reveal the compositional and chemical state of the product. Figure S4 (Supporting Information) presents a typical XPS pattern of the as‐prepared product and is consistent with previously observed in Bi 2 S 3 .…”

Improving the Field‐Effect Performance of Bi2S3 Single Nanowires by an Asymmetric Device Fabrication

“…[6][7][8][9][10] Further explorations, from material growth to characterization, are still needed. [37,38] However, there are only few works reported on Bi 2 S 3 single-NW transistors, except for those from Yao's research. [14][15][16][17][18] Furthermore, in recent years, many researches have also focused on performance improvements of the nanodevices for better applications.…”

“…such as photolithography, 1D nanostructures have further extended their applications in nanolasers, field-effect transistors, phototransistors, photodetectors, light-emitting diodes (LEDs), and solar cells. [37,38] However, there are only few works reported on Bi 2 S 3 single-NW transistors, except for those from Yao's research. [29][30][31] There are also many articles published on its application in photodetectors and solar cells.…”

“…[36] In our previous works, we also explored the photoresponsive behavior of solvothermal-process-synthesized Bi 2 S 3 nanowires (NWs) at low temperature and with different electrical contacts. [37,38] However, there are only few works reported on Bi 2 S 3 single-NW transistors, except for those from Yao's research. [39,40] Herein, we synthesize Bi 2 S 3 NWs by the chemical vapor deposition (CVD) method to further improve its crystalline quality.…”

Effect of Electrical Contact on the Performance of Bi2S3 Single Nanowire Photodetectors

“…[33,34] In previous work, we investigated the photoresponsive behavior of Bi 2 S 3 NW films at low temperatures, which was distinctly different from that at room temperature. [35] Herein, we fabricated photodetectors based on long single-crystalline Bi 2 S 3 NWs with different electrical contacts and explored their respective performance. We synthesized long Bi 2 S 3 NWs and investigated their detailed electrical contact effects on the performance of NW photodetectors.…”