Luminescent Ge-related centre in high-pressure synthesized diamond

TL;DR

This paper reports the synthesis of high-quality diamonds with luminescent germanium-related centers, revealing detailed electronic structure and isotope shifts, advancing understanding of Ge impurities in diamond lattices.

Contribution

It introduces a novel high-pressure synthesis method for diamonds with Ge-related luminescent centers and characterizes their electronic and vibrational properties.

Findings

Observation of four-line fine structure at 2 eV in luminescence

Identification of isotope shifts confirming Ge impurity

Proposal of a split-vacancy structure for the Ge center

Abstract

We report on the high-pressure synthesis of novel nano- and microcrystalline high-quality diamonds with luminescent Ge-related centers. Observation of the four-line fine structure in luminescence at 2 eV (602 nm) at temperatures below 80 K manifests a high quality of diamonds. We demonstrate germanium and carbon isotope shifts in the fine structure of luminescence at 602 nm and its vibrational sideband which allows us to unambiguously associate the center with the germanium impurity entering into the diamond lattice. We show that there are two ground-state energy levels with the separation of 0.7 meV and two excited-state levels separated by 4.6 meV in the electronic structure of the center and suggest a split-vacancy structure of this center.