Recently, the team of Quantum Information Technology Center of Chongqing Institute of Green & Intelligent Technology, Chinese Academy of Sciences made the latest progress in the preparation of IVAVIB large-area monolayer material represented by GeSe, the determination of the band structure and the device testing and analysis.
Nearly 100 types of 2D materials have been discovered, including the fourth main group of simple elements, the third and fifth main group consisting of binary compounds, metal chalcogenides, complex oxides, etc. These findings not only broke the long time Two-dimensional crystals can not be stable in nature, saying that their own characteristics are showing many novel physical phenomena and electronic properties, such as semi-integer, fractional and fractal quantum Hall effect, high mobility, band structure transformation, etc. The IVAVIB single crystal MX (M = Ge, Sn; X = S, Se) is characterized by its high stability, environmental friendliness, rich reserves and similarities in material properties to black phospholene Has been widely concerned.Based on the first principle method for calculating the energy band structure of MX, the critical layer thickness from indirect bandgap to direct band gap and the theoretical predictions of piezoelectric properties based on its C2v symmetry structure However, due to its brittleness, it is difficult to fabricate monatomic layer materials directly by physical tearing methods due to its brittleness, and it is also difficult to obtain large area monolayers (more than 1 micron) by chemical synthesis methods. IV AVIB single crystal two-dimensional material research so far still remain in the theoretical prediction stage.
In MX, GeSe is theoretically considered to be the only material with a direct bandgap, and the spectral coverage of the material covers almost the entire spectrum of sunlight, making it a huge area for quantum optics, photodetection, photovoltaics, and electricity Of the application potential.Accordingly, Chongqing Institute of Quantum Information Technology Center team found that the use of silicon surface silicon dioxide insulation and laser thinning method, the laser power density can be continuously thinning GeSe layer Thick, until the single atomic layer.The thinning mechanism is the laser heat generated in the GeSe surface layer, due to the layered nature of GeSe material itself, it is difficult to heat the timely transfer out, resulting in layer thickness is continuously thinning.When the thickness of GeSe is reduced As thin as the monatomic layer, the entire SiO2 / Si can be regarded as a heat sink and can not be further thinned.Using this method, the team first experimentally prepared a GeSe monolayer material with a thickness of 100 microns or more, based on the fluorescence spectrum, Raman Spectrum and other methods to study the atomic and energy band structure of the GeSe single atomic layer and verify the reliability of the experimental results based on the first-principle method theory.Experiments and theoretical calculations show that the GeSe The atomic fluorescence spectrum of the atomic layer is very wide, from the visible to the near-infrared band found eight fluorescence peaks, indirect bandgap to direct bandgap transition occurred in the third layer.In addition, the team were experimentally prepared based on GeSe body Materials and two-dimensional materials, the IV and photoreaction properties show that the photosensitivity of the two-dimensional material is 3.3 times that of the corresponding material, and the photoreactivity of the two-dimensional material device is also far superior to that of the corresponding bulk material device.
Relevant research results have been published in Advanced Functional Materials, which is supported by the major frontier projects of Chongqing Municipality, A type of young scholars in the western part of the Chinese Academy of Sciences, and the grant from the National Natural Science Foundation of China.
