The large-scale, single-crystal rhombohedral boron nitride (rBN) layers with robust ferroelectricity hold significant potential for various applications in the field of electronics and optoelectronics. One key application is in the development of high-performance ferroelectric devices such as non-volatile memories, ferroelectric field-effect transistors, and sensors. The robust and switchable ferroelectric properties of rBN can enable the creation of energy-efficient and fast-operating memory devices. Additionally, the unique optical nonlinearity of rBN can be harnessed for applications in photonics, such as in the development of optical modulators and switches. The high thermal conductivity of rBN also makes it suitable for applications in thermal management systems, where efficient heat dissipation is crucial.