Study On Preparation Of Two Dimensional ?-GeTe And Its Properties

Since the discovery of graphene in 2004,two-dimensional?2D?semiconductor materials have become a hot research field.Compared with their bulk counterparts,2D semiconductor materials are promising in electronics/optoelectronics,catalysis,energy storage and transformation,sensors and other fields because of their unique and excellent properties,such as outstanding mechanical properties,ultrahigh room-temperature carrier mobility,and very large specific surface areas.At present,however,some drawbacks of discovered 2D materials limit their application,and the exploration of new 2D materials with better semiconductor properties is therefore of crucial importance.In this paper,we optimized and simulate crystal structure of?-GeTe by Material Studio and the theoretical calculations of bulk and monolayer are?-GeTe carried out based on first-principles firstly.The results of simulations and calculations show that?-GeTe is a layered material and the interlayer distance is 3.58?.No soft phonon modes are observed in the calculated phonon dispersion plot of monolayer?-GeTe,which confirms its kinetic stability.The calculations of electronic structure demonstrate bulk?-GeTe is an indirect band gap semiconductor with narrow band gap,however,its band gap is wider?1.84 eV?when it becomes monolayer structure.The spectra of the dielectric function of monolayer?-GeTe shows that there are two wider absorption peaks in³.8 and⁶.3 eV?ultraviolet region?,indicting 2D?-GeTe is promising in optoelectronics areas,especially in ultraviolet region.We prepared?-GeTe nanosheets by sonication-assisted liquid-phase exfoliation method,and the optimum experimental condition can be determined?the solution is ethanol;the sonication time is 12 h;the centrifugal speed is 5000 r/min?.We can obtain few-layer or bilayer/monolayer?-GeTe nanosheets,and the thickness of monolayer?-GeTe is 1.6 nm.The optical band gap of?-GeTe nanosheets is about1.93 eV characterized by UV-vis-NIR spectroscopy which is similar to the result of calculation.And we find?-GeTe nanosheets are sensitive to Fe³⁺,and the fluorescence intensity of?-GeTe nanosheets decrease when added Fe³⁺into?-GeTe nanosheets dispersion?Sol-B?.The fluorescence intensity decrease in proportion to the increase of the concentration of Fe³⁺and the detection limitation is0.052?M.The mechanism of fluorescence quenching can be ascribed to static quenching because of the stable florescence lifetime of?-GeTe nanosheets in the presence and absence of Fe³⁺.