Oxygen in diamond: Thermal stability of ST1 spin centres and creation of oxygen-pair complexes

Little is known about oxygen-related defects in diamond. Recently, the promising room-temperature spin centre named ST1 was identified as an oxygen centre, but of still unknown atomic structure and thermal stability. In this work, we report on the optically active oxygen-related centres and the conditions for their formation, using ion implantation of oxygen in various conditions of depth and fluence. More specifically, we establish the temperature formation/stability range of the ST1 centre, which has a maximum at about 1100 °C and is narrower than for NV centres. In these conditions, optically detected magnetic resonance (ODMR) on small ST1 ensembles was measured with a spin readout contrast of >20% at 300 K. In cathodoluminescence, the 535 nm ST1 peak is not observed. Besides, a broad peak centred at 460 nm is measured for implantation of O 2 molecular ions. For an annealing temperature of 1500 °C, a different centre is formed (with ZPL at 584.5 nm) with an intensity increasing with a power law 1.5 20%) spin readout contrast is achieved • For annealing temperatures ≥1500 °C, a complex including two oxygen atoms forms