Carbon incorporation in boron nitride grown by MOCVD under N 2 flow P.A. Caban a , P.P. Michalowski a , I. Wlasny b , J. Gaca a , M. Wojcik a , P. Ciepielewski a , D. Teklinska a, * , J.M. Baranowski a a Lukasiewicz Research Network - Institute of Electronic Materials Technology, Wolczynska 133, 01-919, Warsaw, Poland b Faculty of Physics, University of Warsaw, Pasteura 5, Warsaw, Poland article info Article history: Received 26 April 2019 Received in revised form 18 September 2019 Accepted 19 September 2019 Available online 20 September 2019 Keywords: Metalorganic chemical vapour deposition Boron nitride epitaxy Nitrides SIMS characterization abstract Boron Nitride (BN) films were grown on 2-inch sapphire substrates using metal organic chemical vapour deposition (MOCVD) using two different carrier gases, nitrogen and hydrogen. Structural properties of grown BN films were systematic investigated. SIMS measurements reveal that BN films grown under nitrogen flow are strongly carbon contaminated, predominantly in a form of carbon clusters. It is shown that carbon contamination originates from reactions in which TEB precursor is involved. It is also shown that hydrogen eliminates excess of unreacted carbon. Thus, the MOCVD growth of BN films under H 2 flow is leading to carbon free layers with atomically smooth surface morphology. © 2019 Elsevier B.V. All rights reserved. 1. Introduction Hexagonal boron nitride (hBN) is regarded as a good candidate for dielectric layers, because of its atomically flat surface and the lack of dangling bonds at the surface [1 ,2]. Boron nitride is a wide bandgap semiconductor material and as it was recently established that it is an indirect band gap material [3]. Growth of hBN on wafer scale and insulating substrates is important for realizing commer- cial scale devices. The Metalorganic Chemical Vapour Deposition (MOCVD) is well recognized method for the growth of BN epitaxial layers. The most common substrate is sapphire and often used precursors are triethylboron (TEB) for boron and ammonia (NH 3 ) for nitrogen. There are many publications describing MOCVD growth on sapphire and other substrates [4e12]. The important progress in understanding the MOCVD growth was achieved when it was demonstrated that the growth mode could be changed from 3D to self-terminated one under high reactor pressure and increased of V/III ratio [13e15]. The self-terminated growth mode at high reactor pressure results in atomically smooth 5e6 mono- layer thick BN film [14]. The carrier gas is also an important factor determining the properties of BN layers because it affects the chemical reactions. It has been shown in our previous publication that the 3D growth mode and self-terminated one under Ar flow leads to a high carbon contamination of the BN film [16]. On the other hand, growth in the 3D and self-terminated mode under H 2 flow leads to elimination of unreacted carbon by more than four orders of magnitude. The H 2 may react with carbon leading to methane and allow to get carbon clean BN films [16]. Nitrogen as carrier gas has been considered as a source of ni- trogen atoms [17 , 18]. Other recent work provides an analysis of BN film grown with different carrier gases H 2 and N 2 and reported that BN grown with N 2 carrier gas contains more defects compared to film grown with H 2 [19]. However, the mechanism responsible for this result has not been explained. Research presented in this work is connected with MOCVD grown BN films under N 2 and H 2 gas flow. Our previous research has shown that the MOCVD growth under Ar flow leads to very high carbon contamination reaching several percent [16]. Motiva- tion behind present work is to investigate if the growth under N 2 flow leads to high carbon contamination as well. This will allow to establish that TEB is the origin of carbon contamination of the BN films. * Corresponding author. E-mail address: dteklinska@gmail.com (D. Teklinska). Contents lists available at ScienceDirect Journal of Alloys and Compounds journal homepage: http://www.elsevier.com/locate/jalcom https://doi.org/10.1016/j.jallcom.2019.152364 0925-8388/© 2019 Elsevier B.V. All rights reserved. Journal of Alloys and Compounds 815 (2020) 152364