Figure 1

Series of images from an STM movie [12] during a continuous ramp from 300 to 1057 K. (a) The Rh(111) surface directly after exposure to 40 L of borazine gas at room temperature. A monoatomic step on the Rh surface crosses the image. The rough appearance of the upper and lower terraces is caused by the borazine deposit. (b) At higher temperatures, the overlayer first organized into narrow, elongated $h$-BN islands. The height variations within the islands result from the mismatch between the lattice constants of the overlayer and the substrate. (c) The next stage was the formation of more compact $h$-BN islands with a defective nanomesh superstructure. (D) At the final temperature the nanomesh structure was relatively well defined. Image size $85\mathrm{nm}\times 85\mathrm{nm}$; sample voltage $V_b=3.0\mathrm{V}$; tunneling current $I_t=0.05\mathrm{nA}$.Reuse & Permissions

Figure 2

Images from an STM movie [12] of an $h$-BN island on Rh(111) during borazine deposition at 978 K. (a) The initial island, obtained by 0.2 L borazine exposure at room temperature and subsequent annealing at 978 K. (b) After 368 s of borazine exposure at $2.5\times {10}^{-9}\mathrm{mbar}$ at 978 K; the island had become triangular within the first 60 s. (c) After 421 s new kinks had formed on the right edge, while the kink at the bottom edge had advanced to the right corner. The inset is a sketch indicating the two edge types, the red one having the higher energy. (d) After 473 s the two kinks on the right edge had advanced and new kinks had formed on the lower edge. Image size $65\mathrm{nm}\times 65\mathrm{nm}$; $V_b=1.0\mathrm{V}$; $I_t=0.05\mathrm{nA}$; 52.5 s per image.Reuse & Permissions

Figure 3

An $h$-BN overlayer can be formed without breaking B-N bonds, by combining the intact $(\mathrm{BN}{)}_3$ rings originating from borazine molecules. Blue solid lines denote bonds in the original molecules; the dashed ones are new and have formed in combination with the loss of hydrogen. The red solid line shows that only by cutting B-N bonds the island can develop two different types of edges, as seen in the STM images (e.g., Fig. 2), either N or B terminated.Reuse & Permissions

Figure 4

(a)–(c) Three subsequent images from an STM movie [12] showing the formation of a defect line in the $h$-BN nanomesh overlayer during growth in $1.2\times {10}^{-9}\mathrm{mbar}$ borazine at 978 K. The two merging islands share the same orientation but have a translational mismatch that remains visible after coalescence as a row of deformed nanomesh unit cells. These lines were surprisingly immobile, as is illustrated in (d), which was taken after the deposition had been completed and the fully $h$-BN covered Rh surface was heated further to 1135 K.Reuse & Permissions