Low-temperature photoluminescence study of optical centers in HPHT-diamonds

The properties and creation of optical centers in diamond are essential for applications in quantum technology. Here, we study the photoluminescence (PL) spectroscopy behavior at low temperatures of diamond subjected to electron irradiation and annealing heat treatment. Through temperature variation testing, it was found that the NV⁻ center intensity of diamond with a nitrogen content of 150 ppm before treatment is insensitive to the experimental temperature, but significantly increases with decreasing temperature after treatment, showing sensitivity to temperature. In addition, the H3 center also shows an increasing trend with decreasing temperature. The results of annealing diamond with a nitrogen content of 730 ppm showed that even at a low temperature of 93 K, no NV⁻ centers were detected, but there were a large number of Ni-N related centers, especially NE8 centers. Our findings can promote a deeper understanding of the behavioral characteristics of HPHT-diamond optical centers in low-temperature environments.