The research team of Professor Chen Xianhui of the National Laboratory for Physical Sciences at Microscale collaborated with Professor Zhang Yuanbo, Professor Feng Donglai and Professor Wu Hua of Fudan University to make important progress in the research of two-dimensional graphene-like field effect transistors. Nano-thick two-dimensional black phosphorus field effect transistor. The discovery of graphene with a single layer of atomic thickness marks the advent of two-dimensional crystals as a class of materials that may affect human future electronic technology. However, the electronic structure of two-dimensional graphene does not have an energy gap, and cannot be turned on and off in electronic applications, which weakens its use to replace semiconductor switches in computer circuits. Scientists began to explore alternative materials, hoping to overcome the shortcomings of graphene, and proposed several possible alternative materials, such as single-layer silicon and single-layer germanium, but these materials are unstable in the air, which is not conducive to practical applications. It is of great significance and challenge to further explore two-dimensional materials with new functions and practical applications.
They successfully prepared a field effect transistor based on a two-dimensional black phosphorus single crystal with an energy gap. Compared with other two-dimensional crystal materials, the two-dimensional black phosphorus single crystal material is more stable, but its single crystal is not easy to grow under normal pressure. Dr. Ye Guojun, a doctoral student of Chen Xianhui's research group, used the high-temperature and high-pressure synthesis equipment purchased by the school to successfully grow high-quality black phosphorus single crystal materials under the extreme conditions of high temperature and high pressure, which laid the foundation for the realization of two-dimensional black phosphorus single crystal materials. Subsequently, Chen Xianhui's group and Zhang Yuanbo's group used mechanical tape to peel off the flakes from the bulk single crystal and attached it to a silicon wafer coated with silicon dioxide. Based on this, the field effect was prepared. Transistor.
Experiments show that when the thickness of the two-dimensional black phosphorous material is less than 7.5 nanometers, it can obtain reliable transistor performance at room temperature, the modulation amplitude of the leakage current is in the order of 100,000, and the current-Voltage characteristic curve shows a good current saturation effect. The charge carrier mobility of the transistor also shows a dependence on the thickness. When the thickness of the two-dimensional black phosphorous material is 10 nm, the highest mobility value is about 1000 square centimeters per volt per second. These properties show that the two-dimensional black phosphorus field effect transistor has great potential in the application of nanoelectronic devices.
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