Chemical Interaction-Guided, Metal-Free Growth of Large-Area Hexagonal Boron Nitride on Silicon-Based Substrates

Abstract

Hexagonal boron nitride (h-BN) is an ideal platform for interfacing with two-dimensional (2D) nanomaterials to reduce carrier scattering for high-quality 2D electronics. However, scalable, transfer-free growth of hexagonal boron nitride (h-BN) remains a challenge. Currently, h-BN-based 2D heterostructures require exfoliation or chemical transfer of h-BN grown on metals resulting in small areas or significant interfacial impurities. Here, we demonstrate a surface-chemistry-influenced transfer-free growth of large-area, uniform, and smooth h-BN directly on silicon (Si)-based substrates, including Si, silicon nitride (SiN), and silicon dioxide (SiO), via low-pressure chemical vapor deposition. The growth rates increase with substrate electronegativity, Si < SiN < SiO, consistent with the adsorption rates calculated for the precursor molecules via atomistic molecular dynamics simulations. Under graphene with high grain density, this h-BN film acts as a polymer-free, planar-dielectric interface increasing carrier mobility by 3.5-fold attributed to reduced surface roughness and charged impurities. This single-step, chemical interaction guided, metal-free growth mechanism of h-BN for graphene heterostructures establishes a potential pathway for the design of complex and integrated 2D-heterostructured circuitry.

Low temperature growth of clean single layer hexagonal boron nitride flakes and film for graphene-based field-effect transistors

“…The observed B 1s and N 1s binding energies are peaked at 190.37 and 397.97 eV, respectively ( Fig. 2a, b), corresponding to the previously-reported locations of h-BN products [5, [8][9][10][11][12][13][14][15][16][17][18]. The atomic ratio of B/N analyzed from the XPS data is about 1.10, approaching 1/1 stoichiometry in h-BN.…”

“…Recently, several methods have been developed to grow monolayer or multi-layer h-BN film. In these methods, chemical vapor deposition (CVD) is very popular for obtaining high yield, better quality and controllable h-BN film on different metal substrates (Cu, Ni, Pt) at growth temperature as high as 1,000°C [8][9][10][11][12][13][14][15][16][17][18]. While exfoliated h-BN films are demonstrated to be a super dielectric layer for graphene devices, in practice, the performance of asgrown products as dielectric substrate of graphene fieldeffect transistor (FET) devices is dependent on the quality of h-BN and interface properties between graphene and h-BN [8].…”

Atomically Thin Hexagonal Boron Nitride and Its Heterostructures

“…[ 22,35 ] To make it reality, several elaborate methods on the substrates including pretreatment, alloying and orientation controlling, have been adopted to modulate h‐BN nucleation density and nucleation orientation. [ 31–35 ] To date, single‐crystal metal (Cu (111), [ 36 ] Cu (110), [ 21 ] Ni (111), [ 37,38 ] Au (111), [ 39 ] Rh (111), [ 40,41 ] Ir (111), [ 42,43 ] Ru (0001), [ 44 ] Re (0001)), [ 45,46 ] polycrystalline metal substrates (Cu, [ 30,47 ] Ni, [ 48,49 ] Fe, [ 50,51 ] Pt [ 52,53 ] ), alloys (Cu–Ni, [ 54–57 ] Fe–Ni, [ 58,59 ] Ni–Ga 60 ), and nonmetal substrates (SiO 2 , [ 61,62 ] Si 3 N 4 , [ 63 ] sapphire [ 64 ] ) are all employed to grow h‐BN via CVD process. Recently, there is an increasing interest on liquid‐metal substrates, which can control the orientation of h‐BN nucleation or domains due to its quasi‐atomically smooth surface and excellent fluidity.…”

Direct growth of hexagonal boron nitride on non-metallic substrates and its heterostructures with graphene

“…The h-BN layer exhibits a large electrical bandgap (∼5.97 eV) ( Laturia et al., 2018 ), has an atomically smooth surface with little to no dangling bonds and/or surface trap states (C. R. Dean et al., 2010 ), and also serves as an ideal gate dielectric (6.82–6.93 in-plane) substrate for graphene and other 2D semiconductors ( Laturia et al., 2018 ). Some other notable characteristics of h-BN (as shown in Figure 1 ) are (A) dispersion of solution processed h-BN in water as well as in organic solvents ( Lin et al., 2011 ; Zhu et al., 2015 ), (B) ferroelectricity in AB stacked h-BN ( Yasuda et al., 2021 ), (C) permeability to thermal protons in its monolayer form ( Hu et al., 2014 ; Lozada-Hidalgo et al., 2016 ), (D) interlayer tunneling in a heterojunction solar cell or photodetectors or memory devices ( Vu et al., 2016 ; Wang et al., 2020 ; Won et al., 2021 ), (E) a gate dielectric substrate ( Behura et al., 2017 ), and (F) quantum emission ( Fröch et al., 2020 ; Schell et al., 2018 ; Yim et al., 2020 ).

Figure 1 Crystal structure and properties of hexagonal boron nitride (h-BN), a 2D insulator (A–D) The unique properties of h-BN include (A) dispersion inks (Reprinted with permission from ( Zhu et al., 2015 ).

…”