Antireflection properties of germanium-carbon coating on zinc supplied substrate

摘要

In this research, germanium-carbon coatings were deposited on ZnS and glass substrates by a RF plasma enhanced chemical vapor deposition method using GeH_4 and CH_4 as precursors. ZnS/Ge_(1−x)C_x double-layer antireflection coating with optical thickness of one quarter wavelength was designed. The samples were characterized by fourier transform infrared spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy and nanoindentation. The coatings exhibited a structure free of pores with a very good adhesion to substrate. Based on the XRD patterns, no diffraction peak was found, so all the coatings mainly had an amorphous structure. The infrared (IR) transmittance spectrum show that the maximum IR transmittance in the band of 1030-1330 cm~(−1) was about 84.6%, which is higher than ZnS substrate by 10%. In addition, the reflection of ZnS substrate is about 25%. This system has reduced the reflection from the substrate by 15%.