Shape evolution of two dimensional hexagonal boron nitride single domains on Cu/Ni alloy and its applications in ultraviolet detection.

Two dimensional (2D) hexagonal boron nitride (h-BN) has attracted extensive attention due to its high thermal and chemical stability, excellent dielectric characteristic, and unique optical properties. However, the chemical vapor deposition synthesis of 2D h-BN is not fully explored, such as morphology regulation and size control. Here we demonstrate the growth of 2D h-BN single domains on Cu/Ni alloy via atmospheric chemical vapor deposition (APCVD). We discover that the shape of the as-grown h-BN single domains can be controlled from triangles, hexagons, to circles by adjusting the Ni content of the Cu/Ni substrates. Moreover, we find out that increasing the nickel content can suppress the nucleation density while the average domain size is accordingly improved. The grown single-crystalline h-BN demonstrates ultralow dark current about 0.9 pA and outstanding ultraviolet response with the responsivity up to 5.45 mAW. The response time are 376 and 198 ms. Our work sheds light on the controllable synthesis of 2D h-BN and promotes its applications in high ultraviolet detection.