Tuning colour centres at a twisted hexagonal boron nitride interface

The colour centre platform holds promise for quantum technologies, and hexagonal boron nitride has attracted attention due to the high brightness and stability, optically addressable spin states and wide wavelength coverage discovered in its emitters. However, its application is hindered by the typically random defect distribution and complex mesoscopic environment. Here, employing cathodoluminescence, we demonstrate on-demand activation and control of colour centre emission at the twisted interface of two hexagonal boron nitride flakes. Further, we show that colour centre emission brightness can be enhanced by two orders of magnitude by tuning the twist angle. Additionally, by applying an external voltage, nearly 100% brightness modulation is achieved. Our ab initio GW and GW plus Bethe-Salpeter equation calculations suggest that the emission is correlated to nitrogen vacancies and that a twist-induced moire potential facilitates electron-hole recombination. This mechanism is further exploited to draw nanoscale colour centre patterns using electron beams. Colour centre emission from hexagonal boron nitride (hBN) holds promise for quantum technologies but activation and tuning are challenging. Here, the authors show twist-angle emission brightness tuning and external voltage brightness modulation at the twisted interface of hBN flakes.

Automated summary

Colour centre emission from hexagonal boron nitride (hBN) shows promise for quantum technologies, but activation and tuning are challenging. In this study, the authors demonstrate the tuning of emission brightness by adjusting the twist angle and modulation of brightness with external voltage at the twisted interface of hBN flakes.