Recently, a research team from the Shanghai Institute of Optics and Fine Mechanics (SIOM), Chinese Academy of Sciences (CAS) carried out systematic research on the heteroepitaxial growth of diamond on YAG crystals for the thermal management of the crystal. The related research results have been published in Materials Chemistry and Physics on August 16, 2021.

Diamond is the material of first choice for thermal management applications because of the highest thermal conductivity, extremely stable physical and chemical properties. Otherwise, diamond can be used to improve the performance of laser due to its excellent heat dissipation. Thus, there are great challenges to diamond processing.

In order to solve this problem, the researchers proposed another way for the thermal management of solid-state lasers, which is directly depositing diamond films on the laser host material.

In this research, Scientists selected the YAG single crystal as the substrate, and the MPCVD deposition of diamond films on this type of laser host material was systematically studied. The results reflect that depositing a nano-thick carbon film on the substrate before the MPCVD growth can effectively increase the subsequent diamond nucleation density, which is beneficial for obtaining a continuous film. On the other hand, a relatively high temperature and low methane concentration during the deposition process are beneficial to decrease the defect density and improve the quality of the diamond film, as it promotes the reduction of defects by H atoms.

The deposition of the diamond film had effectively improved the thermal performance of the YAG substrate, while its optical properties were almost unaffected, which meet the requirement of laser applications.

The method of this work can also be applied to other laser materials that are quite stable in methane-hydrogen plasma, which may have broad application prospects in solid-state lasers fields.

This work was supported by the Natural Science Foundation of China and Shanghai Sailing Program.

Fig1. Surface morphology and thermal properties of different samples. (Image by SIOM)