Directional etching for high aspect ratio nano-trenches on hexagonal boron nitride by catalytic metal particles

Stimulated by the attractive performance of multi-dimensional heterostructures involving hexagonal boron nitride (hBN), intense attentions have been paid to creation of sharp boundary/interface, which could bring hBN nano-structures additional appealing physical properties. However, the lack of controllable synthesis limits further experimental investigation on hBN nano-structures. Here, the directional etching of transitional metal nano-particles (NPs) on the surface of hBN to produce nano-trenches with sharp edges was systematic investigated. It is found that, only Pt and Ir NPs can produce armchair-oriented nano-trenches at low H-2 partial pressure, while other transitional metals lead to zigzag oriented nano-trenches. The density and width of the nano-trenches always increase with etching temperature and the pre-treated solution concentration while the trench orientation depends on both H-2 partial pressure and etching temperature. The aspect ratio of nano-trenches may reach several thousand under optimized conditions. The method exhibited here shines a light on edge-selective patterning of 2D crystals.

Automated summary

This study investigates the directional etching of transition metal nanoparticles on the surface of hBN to produce nano-trenches with sharp edges. The orientation and shape of the trenches depend on the type of transition metal used, while the density and width of the trenches are affected by the etching temperature and solution concentration.