Large-area single-crystal hexagonal boron nitride: From growth mechanism to potential applications

To date, chemical vapor deposition has been employed to grow large-area polycrystalline (PC) films of hexagonal boron nitride (hBN). However, PC hBN thin films exhibit abundant grain boundaries, small grain sizes, and structural imperfections, which collectively degrade the performance as well as hinder the scalability and potential applications of hBN films. Recently, demonstrated deposition methods for growing large-area single-crystalline (SC) hBN films can break through these bottlenecks and have opened avenues for new opportunities. Large-area SC hBN films outperform their PC counterparts owing to the presence of fewer grain boundaries and a more homogeneous surface morphology. This review article presents a consolidated overview of the growth mechanisms of SC hBN films and role of metal catalysts (substrates) in the growth process. Applications, in which SC hBN outperforms PC hBN as well as the potential applications of SC hBN, are also discussed.