Single photon emission from hydrogen-filled transition metal dichalcogenide bubbles

Single-photon emitters (SPEs) have been observed in strained single layers of Transition Metal Dichalcogenides (TMDs) at cryogenic temperatures. Several approaches have been investigated, but the achievement of regular arrays of controllably strained areas, and thus of controlled SPEs, remains a challenge. Here, we discuss the possibility of exploiting strained single-layered TMD bubbles containing highly pressurised hydrogen, which can be controllably created in an ordered fashion by lithography-based approaches. While these structures would deflate at cryogenic temperatures due to the liquefaction of hydrogen, we discovered that the deposition of few-layer-thick hexagonal boron nitride (hBN) on top of the TMD bubbles allows them to maintain their shape, even for temperatures as low as 5 K. By performing Raman measurements on the bubbles, we were able to track the strain behaviour of the system at different temperatures, showing that biaxial strains as high as 1.6% are achieved even at 5 K. Micro-photoluminescence (mu -PL) mu- PL) studies of hBN-capped WS2 bubbles at cryogenic temperatures demonstrated the presence of quantum emitters on the edges of several bubbles. The SPEs were characterised through magneto-mu -PL mu- PL and time-resolved measurements.