Abstract
Boron carbonitride (BCN) films containing hybridized bonds involving elements B, C, and N over wide compositional ranges enable an abundant variety of new materials, electronic structures, properties, and applications, owing to their semiconducting properties with variable band gaps. However, it still remains challenging to achieve band gap-engineered BCN ternary with a controllable composition and well-established ordered structure. Herein, we report on the synthesis and characterization of hybridized BCN materials, consisting of self-ordered hexagonal BN (h-BN) crystalline nanodomains, with its aligned basal planes preferentially perpendicular to the substrate, depending on the growth conditions. The observation of the two sets of different band absorptions suggests that the h-BN nanodomains are distinguished enough to resume their individual band gap identity from the BCN films, which decreases as the carbon content increases in the BCN matrix, due to the doping and/or boundary effect. Our results reveal that the structural features and band gap of this form of hybrid BCN films are strongly correlated with the kinetic growth factors, making it a great system for further fundamental physical research and for potential in the development of band gap-engineered applications in optoelectronics.
Highlights
The atomic bonding similarity amongst boron (B), carbon (C), and nitrogen (N) allows for the formation of a ternary boron carbonitride (BCN) system with a wide compositional range, including typical materials, such as diamond, graphite, fullerene, cubic BN (c-BN), hexagonal BN (h-BN), B4 C, C3 N4, BCN, BC2 N, and so on [1,2,3], when combining their properties, making them adaptable for diverse applications [4,5,6]
The BCN films with oriented crystalline h-BN nanodomains were prepared at various substrate temperatures in pure Ar gas on the Si substrate
Nanodomains, with its basal planes perpendicular to the substrate, demonstrating the structural evolution and optical band gap that have been controlled via growth kinetics
Summary
The atomic bonding similarity amongst boron (B), carbon (C), and nitrogen (N) allows for the formation of a ternary boron carbonitride (BCN) system with a wide compositional range, including typical materials, such as diamond, graphite, fullerene, cubic BN (c-BN), hexagonal BN (h-BN), B4 C, C3 N4 , BCN, BC2 N, and so on [1,2,3], when combining their properties, making them adaptable for diverse applications [4,5,6]. Hybridizing between semi-metallic graphite and insulating BN [7], BCN ternary exhibits excellent semiconducting properties with an adjustable band gap, making it a suitable candidate in optoelectronic devices, luminescent devices, transistors, and micro-electrical-mechanical system (MEMS), just to name a few [8,9,10,11,12]. Recent studies on the optical and electronic properties of the BCN system have indicated that the band gaps of BCN compounds are determined by the elemental constitution, and by other structural properties. The optical band gap value differs from 1.48 to 3.64 eV for BCN films with the same stoichiometry [13,14,15]. The band gap value of the BC2 N films was found to depend on the measurement method [16]. A band gap of BCN nanosheets can be opened or shrunk by hybridizing the h-BN domains in a graphene matrix [17], or the graphene domains in a Coatings 2019, 9, 185; doi:10.3390/coatings9030185 www.mdpi.com/journal/coatings
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