Effect of Si, Ge and Sn dopant elements on structure and photoluminescence of nano- and microdiamonds synthesized from organic compounds

HPHT synthesis of diamonds from hydrocarbons attracts great attention due to the opportunity to obtain luminescent nano- and microcrystals of high structure perfection. Systematic investigation of diamond synthesized from the mixture of hetero-hydrocarbons containing dopant elements Si or Ge (C24H20Si and C24H20Ge) with a pure hydrocarbon – adamantane (C10H16) at 8 GPa was performed. The photoluminescence of SiV− and GeV− centers in produced diamonds was found to be saturated when Si and Ge contents in precursors exceed some threshold values. The presence of SiC or Ge as second phases in diamond samples with saturated luminescence indicates that ultimate concentrations of the dopants were reached in diamond. It is shown that SiC inclusions can be captured by growing crystals and be a source of local stresses up to 2 GPa in diamond matrix. No formation of Ge-related inclusions in diamonds was detected, which makes Ge more promising as a dopant in the synthesis method. Surprisingly, the synthesis of diamonds from the C24H20Sn hetero-hydrocarbon was ineffective for SnV− formation: only fluorescence of N-and Si-related color centers was detected at room temperature. As an example of great potential for the synthesis method, mass synthesis of 50-nm diamonds with GeV− centers was realized at 9.4 GPa. Single GeV− production in individual nanodiamond was demonstrated. [Display omitted] •Saturation in PL intensity of SiV− and GeV− defects is reached in doping of diamond.•Compressed SiC inclusions are detected in HPHT diamonds with SiV− centers.•No formation of the Ge inclusions is detected in diamonds grown in the CHGe system.•Mass synthesis of nanodiamonds with GeV− centers was realized at 9.4 GPa.•Single GeV− production in individual nanodiamond was demonstrated.