Solid State Communications 150 (2010) 2262–2265 Contents lists available at ScienceDirect Solid State Communications journal homepage: www.elsevier.com/locate/ssc Band gap and chemically ordered domain structure of a graphene analogue B x C y N z K. Venu a , S. Kanuri a , K. Raidongia b , K.P.S.S. Hembram c , U.V. Waghmare c , R. Datta a,* a International Centre for Materials Science, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore-560064, India b Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore-560064, India c Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore-560064, India article info Article history: Received 28 July 2010 Received in revised form 20 September 2010 Accepted 22 September 2010 by C.S. Sundar Available online 26 September 2010 Keywords: A. BCN A. Semiconductor D. Band gap E. EELS abstract Chemically synthesized few layer graphene analogues of B x C y N z are characterized by aberration corrected transmission electron microscopy and high resolution electron energy loss spectroscopy (HREELS) to determine the local phase, electronic structure and band gap. HREELS band gap studies of a B x C y N z composition reveal absorption edges at 2.08, 3.43 and 6.01 eV, indicating that the B x C y N z structure may consist of domains of different compositions. The K -absorption edge energy position of the individual elements in B x C y N z is determined and compared with h-BN and graphite. An understanding of these experimental findings is developed with complementary first-principles based calculations of the various ordered configurations of B x C y N z . © 2010 Elsevier Ltd. All rights reserved. 1. Introduction The quest for new materials and an understanding of their properties has led to the extensive research in science and engineering of carbon nano-tubes and graphene [1–3]. With this motivation, the successful synthesis of graphene analogue materials out of various layered structures has been reported [4–8]. Among various graphene analogue materials, B x C y N z attracts particular attention due to the tunability of its semiconducting band gap with control on its composition. Graphene is a semi- metal whereas BN is an insulator. B x C y N z , an intermediate mixture with composition of graphene and BN, possesses direct band gap semiconducting properties depending on its atomic proportions (x, y, z ) and ordering. Many novel electronic device applications can be realized by utilizing this new class of materials. B x C y N z in the two dimensional nano-structure and in other forms is highly stable and particular interest exists in determining the arrangement of its atoms or phases and their relationship with electronic structures. Theoretically, many configurations of hexagonal BCN with comparable energies (within 1%) have been predicted, and those consisting of motifs with BN 3 interlinked with NB 3 are found to have the lowest energy [4]. The electronic structure was also reported for BC 2 N in the single layer compound for various motifs and the lowest energy structure was found to be a semiconductor with a gap of ∼1.61 eV [9]. Experimentally, * Corresponding author. E-mail address: ranjan@jncasr.ac.in (R. Datta). XPS study provides information on the identification of the bonds between elements but this is based on curve fitting of the absorption peak and only suggestive about the formation of any possible phases. EELS quantification very accurately provides the relative amounts of individual elements in a very small area and this information can only approximate in suggesting the formation of a particular phase. For example, EELS quantification cannot provide information on whether there is a homogeneous distribution of B, C, and N atoms or whether the B x C y N z layer structure is a mixture between graphene and BN. Electron energy loss near edge structure (ELNES) up to 50 eV energy loss from the core absorption edge in a transmission electron microscope has the capability to provide finger printing on the coordination along with high spatial resolution, but due to the unavailability of standards it has not been possible to correlate the energy loss spectra with the exact nature of phases formed in B x C y N z . There was another report on the theoretical computation of the EEL near edge spectra of BCN [10]. The calculation was based on single electron molecular orbital theory. The EELS spectra for h-BN, BC 2 N, BC 3 can serve as guides to compare the experimental spectra of a given B x C y N z composition. Recently, the formation of nano size domains of C doped h-BN and graphene has been reported based on UV absorption spectra for B x C y N z grown by CVD [11]. Here we report the experimental determination of band gap edge absorption by high resolution EELS using a gun monochromator and compare with the first-principles pseudopotential based density functional theory (DFT) calculations of BCN, BC 2 N and BCN 2 with various motifs to understand and predict the presence of phases in a 0038-1098/$ – see front matter © 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.ssc.2010.09.029