Engineering Vacancies in Bi₂S₃yielding Sub‐Bandgap Photoresponse and Highly Sensitive Short‐Wave Infrared Photodetectors

Abstract

Defects play an important role in tailoring the optoelectronic properties of materials. Supported by density functional theory (DFT) calculations, herein it is demonstrated that sulphur vacancies are able to engineer sub‐band gap photoresponse in the short‐wave infrared range due to formation of in‐gap states in Bi2S3 single crystals. Sulfurization and subsequent refill of the vacancies result in faster response but limit the spectral range to the near infrared as determined by the bandgap of Bi2S3. A facile chemical treatment is then explored to accelerate the speed of sulphur deficient (SD)‐based detectors on the order of 10 ms without sacrificing its spectral coverage of the infrared, while holding a high specific detectivity (D*) close to 1015 Jones in the visible–near infrared range and 1012 Jones at 1.6 µm. This work also provides new insights into the role sulphur vacancies play in the electronic structure and, as a result, in sub‐bandgap photoresponse enabling ultrasensitive, fast, and broadband photodetectors.

Compositional engineering of metal-xanthate precursors toward (Bi1−xSbx)2S3 (0 ≤ x ≤ 0.05) films with enhanced room temperature thermoelectric performance

“…The calculated elemental ratio (Bi/S: 39.85/60.15) is in good agreement with the stoichiometry of Bi 2 S 3 , which confirms the formation of stoichiometric Bi 2 S 3 . 67 Different chalcogenide metal-ligand precursors can be mixed to make solid solutions of Group V metals (Bi 1Àx Sb x ) 2 S 3 (0 r x r 0.05), via the so-called ''composition engineering''. The well-defined XRD patterns shown in Fig.…”

Thermoelectric Properties of Substoichiometric Electron Beam Patterned Bismuth Sulfide

“…The peaks in Figure 3 corresponds to uncoordinated Bi, thereby confirming the existence of sulfur vacancies in the 150 films. 36,37,38 The atomic ratio of Bi to S was calculated from the areas of Bi 4f7/2 and S 2p3/2 and the results are summarized in Figure 3 The electrical conductivity of the vacuum annealed samples was measured, and the room temperature values are plotted in Figure 3(c). We concluded that 300 °C was the minimum vacuum annealing temperature necessary to introduce S vacancies that contributed to the total carrier concentration in this system and that 400 °C is the upper boundary in the temperature scale for operation, since the films become mechanically unstable with all sulfur removed according to the XPS analysis [see Supporting Information, Figures S7(c) and (d)].…”

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

“…[ 23 , 24 , 25 , 26 , 27 ] Furthermore, sulfurization can reduce trap density of states of the Bi 2 S 3 and lower 1/ f noise. [ 28 ]…”