a 北京工业大学 固体微结构与性能研究所 固体微结构与性能北京市重点实验室 北京 100124;
b 北京工业大学 材料科学与工程学院 功能材料教育部重点实验室 北京 100124
Preparation and Characterization of Black Phosphorus
Zhang Dandana, Yuan Zhenzhoua, Zhang Guoqinga, Liu Danmina, Yuan Zhenzhoua
a Beijing Key Laboratory of Microstructure and Properties of Advanced Material, Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing 100124;
b Key Laboratory of Advanced Functional Materials, Education Ministry of China, College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124
Black phosphorus has attracted broad interest because of their low-dimensional effect, and has become a new kind of two-dimensional (2D) materials. Phosphorus has several allotropes. Black phosphorus is the most thermodynamic stable in them. As a kind of two-dimensional materials, black phosphorus has high carrier mobility and on/off ratio. The band gap of black phosphorus can be adjusted by its number of layers from 0.3 eV~2 eV. It is of great significance to the development of new infrared and near-infrared optoelectronic devices. Currently, the main methods for preparing black phosphorus are chemical vapor transfer and high energy ball milling methods.
In this paper, black phosphorus was successfully synthesized from red phosphorus via chemical vapor transfer and high energy ball milling methods. Then black phosphorus was put in ethanol for 10 min to liquid exfoliation, in which the ultrasonic power was 400 W. The microstructures and stability of black phosphorus synthesized by two methods were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and differential scanning calorimeter (DSC). In situ electrical measurements of black phosphorus prepared by chemical vapor transfer were performed using a commercial scanning tunnelling microscope-transmission electron microscope probing system (STM-TEM, Nanofactory Instruments) inserted into a JEOL-2010F TEM.
The microstructural characterization results show that there is some red phosphorus and amorphous phases in black phosphorus prepared by high energy ball milling method. On the contrary,the black phosphorus prepared by chemical vapor transfer method has no amorphous phases. The XRD results show that black phosphorus synthesized by chemical vapor transfer method did not change significantly after keeping in the air for 16 days. The DSC results show that the volatile points of the black phosphorus prepared by high energy ball milling and chemical vapor transfer methods are respectively 394.5℃ and 432.2℃, which means the latter has better thermal stability. The TEM results show that a layer or two layers of phosphorene via liquid exfoliation had been obtained, which is large in size and clean in surface. After being irradiated in TEM with a dose of 0.8 eV/(Å2·s) at 200 KV for 60min, few new diffraction spots appeared in black phosphorus synthesized by chemical vapor transfer method, which indicates it is relatively stable under electron radiation in vacuum.
In a word, the black phosphorus prepared by chemical vapor transfer method has lager size, good crystallinity, high purity, and high stability. It can be used to prepare two-dimensional black phosphorus by mechanical exfoliation and liquid exfoliation, and then be applied to advanced microelectronic devices.