(243f) Direct Synthesis of Hexagonal Boron Nitride on SiO2/Si Surfaces Via Chemical Vapor Deposition

The experimental findings of graphene in 2004 and its emerging impact in science and

technology has open the avenues for other two-dimensional (2D) materials including hexagonal

boron nitride (h-BN), transition metal dichalcogenides, black phosphorous etc. Traditionally,

semiconducting 2D materials are being placed on SiO2/Si surfaces for the measurement of

electron transport phenomena. However, the surface roughness and charged impurity associated

with SiO2/Si surfaces reduce the nanoelectronics performance in interfaced 2D materials. In

contrast, h-BN, which is a wide bandgap semiconductor with excellent properties such as:

atomically smooth, lack of dangling bonds, high chemical and thermal stability and can be used

as a gate dielectric for 2D nanomaterials electronics. Currently, there is no direct-growth

mechanism for h-BN and most of the research rely on synthesizing h-BN on metal films and

subsequent transfer for device applications. Considering the important role of ultra-smooth h-BN

in enhancing the carrier mobility of interfaced 2D materials, it is critical to grow large-area h-BN

directly on desired substrates. Here we show high quality, large-scale and uniform h-BN films

synthesized directly on SiO2/Si substrates via surface-interaction guided chemical vapor

deposition (CVD) as confirmed by combined spectroscopic and microscopic analysis. The weak

Raman intensity at â?? 1373 - 1375 cm-1 corresponds to the atomically thin h-BN films. We also

observe that Raman E2g peak position shifts to higher frequency which may be attributed to the

substrate induced stress in the films. Further, the effects of Si crystallography and CVD cooling

conditions on h-BN formations will be discussed. This process of achieving h-BN avoids transfer

related steps for further electrical characterization and integration into semiconductor processing.