High-pressure high-temperature synthesis and characterization of H–S–O multi-doped type IIa diamonds

Nitrogen-valent (NV) color centers exhibit unique quantum and physical properties, making them valuable in advanced scientific research and technical fields. Type IIa diamonds are ideal carriers for NV ⁻color centers. Therefore, the development of methods for incorporating these centers into diamonds is a key research focus. To enhance the preparation techniques, this study introduces a donor impurity element doping method for the successful synthesis of type IIa diamonds containing only NV ⁻color centers. Optical microscopy and scanning electron microscopy characterizations revealed that the introduction of H–S–O impurity elements hindered the synthesis of high-quality diamonds. X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy analyses indicated that incorporating H–S–O into the diamond lattice led to the successful preparation of H–S–O multi-doped IIa diamonds. Photoluminescence results confirmed that these H–S–O multi-doped type IIa diamonds exhibited only NV ⁻ color centers. Additionally, the effects of H–S–O and Al on diamond properties and growth characteristics were thoroughly analyzed through Raman spectroscopy and residual stress analysis. This study provides valuable insights into the origins of natural IIa diamonds and introduces a vital method for preparing NV ⁻color centers in functional IIa diamonds.