Study on the Microstructure of Au/CdZnTe Interface by HRTEM

Abstract

As a new type of detector material, the CdZnTe (CZT) crystal has the advantages such as a wide energy gap, a large average atomic number, the strong ability to stop X- ray and high resistivity. The CZT is not only the best epitaxial substrate to the growth process of infrared detector material—HgCdTe, but also can be widely used in the detector production of X-ray fluorescence analysis, nuclear waste monitoring, airport and port security testing, industrial detection, medical diagnosis, astrophysics research, etc. So it has very broad prospects. Compared with the traditional NaI detector, the CZT detector has a better energy resolution. Compared with Si and Ge detector, it can work at room temperature. So it absorbed great attention in recent years. The structure of the interface between the metal electrode and CZT has great effect on the performance of detector. Au electrode film was prepared on high resistance CZT single crystal by using vacuum evaporation technology in this research. The interface of Au/CZT was investigated by high resolution transmission electron microscope (HRTEM). The results showed that there existed a disordered layer with the thickness of 5-10nm in the interface between the Au electrode and CZT wafer which was only mechanical polished (as opposed to polished and etched) in our present experimental condition. That could be approved as an amorphous layer through diffraction pattern. On the other hand, the interface was flat, smooth and no amorphous layer on which CZT wafer was polished and etched.