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-1. 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.