Color centers in diamond are currently investigated as valid technological building blocks for quantum technologies: they can be applied as single photon emitters for quantum communication and computing or for intriguing quantum sensing applications. Beside the well-known NV- defect, group IV-vacancy centers (SiV, GeV, SnV and PbV) have recently attracted attention due to their narrow and intense emissions, even at room temperature, large Debye-Waller factors, short lifetimes and robust optical coherence [1]. The latter arises by the structure of the defects where the impurity atom (Si, Ge, Sn or Pb) is in a split-vacancy configuration (inversion symmetry group D3d). Among these defects, GeV defect (ZPL at 603 nm) was reported only in 2015 [2] and since then several fabrication methods have been tested. Among them, focused ion beam (FIB) approach allows extremely localized formation of color centers down to the single emitter scale in a mask-less process [3], with excellent positioning and overlays if the irradiation is carried out on a laser interferometer controlled stage. Furthermore, the relatively low irradiation energy (<100 keV) implies a small straggling collision cascade, improving the three-dimensional localization of the final defect. In this work, we report a systematic experiment of fabrication of GeV color centers on electronic grade diamonds using a FIB instrument. The latter is equipped with a liquid metal alloy ion source able to deliver extremely low ion fluences of Ge, Si and Au ions. In particular, the formation yield of GeV defects was studied irradiating arrays of spots with Ge ion fluences ranging from 10 to 1000 units and either 70 or 35 keV implant energies. After thermal annealing in UHV at either 900°C or 1000°C for 2 hours, confocal photoluminescence (PL) analysis measured emission intensities, identified the conditions for single photon emitter formation and evaluated the formation yield (ratio between numbers of emitters per implanted Ge ions). Successively, one of the sample was patterned to create 20 nm diameter pillars around the irradiated spot in order to enhance the GeV emission. A second PL analysis was then carried out to verify the effective enhancement of photon emission. D.G. and E.S. wish to acknowledge the EU HE project: Experimental production capabilities for quantum technologies in Europe (Qu-Pilot). Project ID: 101113983. D.G., E.S., E.M, and R.D.A wish to acknowledge the PNRR MUR project PE0000023-NQSTI. JF wishes to acknowledge the EMPIR project 20IND05 Qadet, co-financed by the Participating States and from the European Union’s Horizon 2020 research and innovation program. [1] C. Bradac, et al. Nat Commun. 10 (2019), 5625 [2] T. Iwasaki, et al. Sci Rep. 5 (2015), 12882 [3] Y. Zhou, et al. New J. Phys. 20 (2018), 125004
Fabrication of GeV color centers in diamond by Focused Ion Beam
Damiano Giubertoni
;Elia Scattolo;Alessandro Cian;Elena Missale;Rossana Dell’Anna;
2024-01-01
Abstract
Color centers in diamond are currently investigated as valid technological building blocks for quantum technologies: they can be applied as single photon emitters for quantum communication and computing or for intriguing quantum sensing applications. Beside the well-known NV- defect, group IV-vacancy centers (SiV, GeV, SnV and PbV) have recently attracted attention due to their narrow and intense emissions, even at room temperature, large Debye-Waller factors, short lifetimes and robust optical coherence [1]. The latter arises by the structure of the defects where the impurity atom (Si, Ge, Sn or Pb) is in a split-vacancy configuration (inversion symmetry group D3d). Among these defects, GeV defect (ZPL at 603 nm) was reported only in 2015 [2] and since then several fabrication methods have been tested. Among them, focused ion beam (FIB) approach allows extremely localized formation of color centers down to the single emitter scale in a mask-less process [3], with excellent positioning and overlays if the irradiation is carried out on a laser interferometer controlled stage. Furthermore, the relatively low irradiation energy (<100 keV) implies a small straggling collision cascade, improving the three-dimensional localization of the final defect. In this work, we report a systematic experiment of fabrication of GeV color centers on electronic grade diamonds using a FIB instrument. The latter is equipped with a liquid metal alloy ion source able to deliver extremely low ion fluences of Ge, Si and Au ions. In particular, the formation yield of GeV defects was studied irradiating arrays of spots with Ge ion fluences ranging from 10 to 1000 units and either 70 or 35 keV implant energies. After thermal annealing in UHV at either 900°C or 1000°C for 2 hours, confocal photoluminescence (PL) analysis measured emission intensities, identified the conditions for single photon emitter formation and evaluated the formation yield (ratio between numbers of emitters per implanted Ge ions). Successively, one of the sample was patterned to create 20 nm diameter pillars around the irradiated spot in order to enhance the GeV emission. A second PL analysis was then carried out to verify the effective enhancement of photon emission. D.G. and E.S. wish to acknowledge the EU HE project: Experimental production capabilities for quantum technologies in Europe (Qu-Pilot). Project ID: 101113983. D.G., E.S., E.M, and R.D.A wish to acknowledge the PNRR MUR project PE0000023-NQSTI. JF wishes to acknowledge the EMPIR project 20IND05 Qadet, co-financed by the Participating States and from the European Union’s Horizon 2020 research and innovation program. [1] C. Bradac, et al. Nat Commun. 10 (2019), 5625 [2] T. Iwasaki, et al. Sci Rep. 5 (2015), 12882 [3] Y. Zhou, et al. New J. Phys. 20 (2018), 125004I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
