A Research Of Preparation Of Molybdenum Disulfide Film And Fabrication Of Photo-detectors Based On Monolayer Molybdenum Disulfide

After 2004 when Geim’s group successfully peeled single-layer carbon（graphene）from the crystalized carbon materials,research of two-dimensional（2D）materials was at its beginning.Then,monolayer of Boron Nitrogen（BN）,Molybdenum Disulfide（MoS₂）and other layered materials were also separated using mechanical exfoliation.These layered materials show us many particular properties,providing numerous possibilities to new electronic devices.After that,researchers and scientists raised the gold rush of 2D materials in the world.Similar to the method of mechanical exfoliation,chemical vapor deposition（CVD）is another way people used to synthesize 2D materials.Its principle is easy that two or more gaseous reactants react in the high temperature environment and the products deposit on the substrate in nucleus growth mechanism.Comparing to mechanical exfoliation,the films producing by CVD have batter uniformity and are always much cleaner.Through improving the equipment and revising the process conditions,in first half of the article,we synthesized large-scaled single-layerMoS₂using controllable CVD method.The lateral size of as produced film is more than 50 micrometers.We have used the scan electron microscopy（SEM）to characterize the sample,the film has good uniformity and the surface of substrate is especially clean.The graphs of atomic force microscopy（AFM）have shown us the thickness of film is around 0.8 nanometers which also demonstrate good step uniformity.We also researched the Raman character and photoluminescence（PL）character of MoS₂ film.We found that the Raman characteristic peak of MoS₂ would change with the variation of thickness of film and the power of incident light.The PL spectrum shown us good fluorescence characteristic of single layer MoS₂ which means 2D MoS₂ is well interacted with the light.By combining the research background and recent development,we are inspired by the excellent fluorescence characteristic of 2D MoS₂.We fabricated the photo-detectors by processing as-grown monolayer MoS₂ sheets,and also we tested various properties of the detectors.The results show that the current-voltage（I-v）curves are much different to the dark condition while the devices are illuminated by visible light,because of the light current under light stimulation.The photo-detectors have shown high responsivity which exponentially increased by the decreasing of the light power.Also the devices have shown the fast photo-response（around 0.1s-0.2s）.As direct band gap semiconductor,single-layer MoS₂ is shown its potential in photoelectronic application because of its excellent performance.In this article,we started from the materials growth to the characterization and analysis,and then to the fabrication and test of devices.We hope these systemic works would provide some new direction to next-generation photoelectronic devices based on 2D MoS₂.