Localization of hexagonal boron nitride color centers using patterned dielectric layers on graphene

One of the most promising building blocks for the development of spin qubits, single-photon sources, and quantum sensors at room temperature, as well as 2D ultraviolet light-emitting diodes, is defect color centers in 2D hexagonal boron nitride (hBN). However, a significant requirement for the realization of such devices toward scalable technologies is the deterministic localization of hBN color centers. Here, we demonstrate a novel approach to the localization of hBN color center emission by using patterned dielectric layers grown on graphene via atomic layer deposition (ALD). While color center emission is quenched within areas where hBN is transferred directly on graphene due to charge transfer, it is maintained where hBN is transferred on micrometer-sized Al2O3 pillars, which act as barriers to charge transfer. Importantly, our approach allows for device architectures where graphene layers are used as top and bottom electrodes for the application of vertical electric fields, such as for carrier injection in electroluminescent devices, Stark shifting of color center emission, and charge state control of defect color centers. Furthermore, the use of ALD to grow dielectric layers directly on graphene allows for the control of tunnel barrier thicknesses with atomic layer precision, which is crucial for many of these device applications. Our work represents an important step toward the realization of a wide range of scalable device applications based on the deterministic localization of electrically controlled hBN color centers.