RESUMEN
The plasmon-enhanced photoresponse properties of a Ag nanoparticle decorated Bi2Se3 nanosheet (AGBS)/p-Si heterojunction device have been studied. The Ag nanoparticles, Bi2Se3 nanosheets, and AGBS nanocomposite are synthesized chemically. Microscopic investigations, ultimately of the AGBS nanocomposite, reveal that the Bi2Se3 nanosheets of thickness â¼20 nm and lateral dimension â¼1 µm are decorated with Ag nanoparticles of sizes 20-40 nm in the nanocomposite. The x-ray diffraction pattern of AGBS shows that apart from being in a metallic state, the Ag in the AGBS is also in the form of compounds with Bi, Se, and additionally O. This observation is further complemented by the x-ray photoelectron spectrum, which shows the presence of Ag0 and Ag+ states of Ag in AGBS. The UV-visible absorption spectra show the plasmonic peak of the Ag nanoparticles occurs at 420 nm; the peak is shifted to â¼500 nm in AGBS due to the modified dielectric environment of the nanoparticles. The AGBS/p-Si heterojunction shows excellent photoresponse properties, with a responsivity of 0.28 A/W, a fairly high detectivity of 4 × 1010 Jones, and an EQE of 71% under 10 V reverse bias at a 500 nm wavelength. The plasmon enhanced photoresponse at the selective wavelength makes this material attractive for high performance optoelectronic devices.
RESUMEN
We report for the first time, the fabrication of novel two-dimensional (2D) p-WS2/n-Si vertical heterostructures with superior junction and photoresponse characteristics. Few layer WS2 has been synthesized by a lithium-ion intercalation technique in hexane and coated on Si substrates for realization of CMOS compatible devices. Atomic force microscopy and Raman spectroscopy have been used to confirm the 2D nature of WS2 layers. Sharp band-edge absorption and emission peaks have indicated the formation of mono-to-few-layers thick direct band gap WS2 films. The electrical and optical responses of the heterostructures have exhibited superior properties revealing the formation of an abrupt heterojunction. The fabricated photodetector device depicts a peak responsivity of 1.11 A W(-1) at -2 V with a broadband spectral response of 400-1100 nm and a moderate photo-to-dark current ratio of â¼10(3). The optical switching characteristics have been studied as a function of applied bias and illuminated power density. A comparative study of the reported results on 2D transition metal chalcogenides indicates the superior characteristics of WS2/n-Si heterostructures for future photonic devices.
