Growth and characterization of 3C-SiC grown using CBr4 as a precursor

The growth of silicon carbide on silicon is being studied for many diverse applications and so the search for precursors that could be used to grow with improved or novel physical, structural and morphological properties is a relevant issue in this field. Here we present a study of the use of CBr4 as a precursor in the deposition of 3C-SiC in a cold walled MOVPE reactor. The growth has been studied in a range of temperatures between 1100 and 1250 ?C, on differently oriented substrates. Additionally, the effect of the C:Si ratio in the gas phase was examined by the addition of propane to the reaction mixture. At lower temperatures faceted crystals grew as islands on the substrate; faceting and 2D planar growth was obtained if higher growth temperatures were applied and at higher C:Si ratios. Atomic force and scanning microscopies revealed interesting growth habits of the island type crystals. Transmission electron microscopy in cross-section confirms that these islands are 3C-SiC and have a high crystal perfection. The crystal habit has been characterised and will be presented. Carbon tetrabromide has revealed itself to be a useful precursor for the growth of SiC and, with a judicious control of the growth conditions could be applied to the growth of thin films and nanocrystals

Nanotechnology for Electronic Materials and Devices

The historical scaling down of electronics devices is no longer the main goal of the International Roadmap for Devices and Systems [...

Material proposal for 2D indium oxide

Realization of semiconductor materials at the two-dimensional (2D) limit can elicit exceptional and diversified performance exercising transformative influence on modern technology. We report experimental evidence for the formation of conceptually new 2D indium oxide (InO) and its material characteristics. The formation of 2D InO was harvested through targeted intercalation of indium (In) atoms and deposition kinetics at graphene/SiC interface using a robust metal organic chemical vapor deposition (MOCVD) process. A distinct structural configuration of two sub-layers of In atoms in "atop" positions was imaged by scanning transmission electron microscopy (STEM). The bonding of oxygen atoms to indium atoms was indicated using electron energy loss spectroscopy (EELS). A wide bandgap energy measuring a value of 4.1 eV was estimated by conductive atomic force microscopy measurements (C-AFM) for the 2D InO.Funding Agencies|FLAG-ERA 2015 JTC project GRIFONE through Swedish Research Council [VR 2015-06816]; National Research Development and Innovation Office, Hungary [NN 118914]; Italian Ministry of Education and Research (MIUR) under the project EleGaNTeMinistry of Education, Universities and Research (MIUR) [PON ARS01_01007]; European Structural and Investment Funds [VEKOP-2.3.3-15-2016-00002]; Swedish Foundation for Strategic Research (SSF)Swedish Foundation for Strategic Research [RIF 14-0074]; Knut and Alice Wallenbergs FoundationKnut &amp; Alice Wallenberg Foundation; [VR 2017-04071]</p

Nanoscale phenomena ruling deposition and intercalation of AlN at the graphene/SiC interface

The possibility for kinetic stabilization of prospective 2D AlN was explored by rationalizing metal organic chemical vapor deposition (MOCVD) processes of AlN on epitaxial graphene. From the wide range of temperatures which can be covered in the same MOCVD reactor, the deposition was performed at the selected temperatures of 700, 900, and 1240 degrees C. The characterization of the structures by atomic force microscopy, electron microscopy and Raman spectroscopy revealed a broad range of surface nucleation and intercalation phenomena. These phenomena included the abundant formation of nucleation sites on graphene, the fragmentation of the graphene layers which accelerated with the deposition temperature, the delivery of excess precursor-derived carbon adatoms to the surface, as well as intercalation of sub-layers of aluminum atoms at the graphene/SiC interface. The conceptual understanding of these nanoscale phenomena was supported by our previous comprehensiveab initiomolecular dynamics (AIMD) simulations of the surface reaction of trimethylaluminum, (CH3)(3)Al, precursor with graphene. A case of applying trimethylindium, (CH3)(3)In, precursor to epitaxial graphene was considered in a comparative way.Funding Agencies|FLAG-ERA 2015 JTC project GRIFONE through Swedish Research Council [VR 2015-06816]; National Research Development and Innovation Office, Hungary NN [118914]; Italian Ministry of Education and Research (MIUR) under project Beyond-NanoMinistry of Education, Universities and Research (MIUR) [PON a3_00363, VR 2017-04071, AF15-557, KAW 2013.0049, AF18-266]; Swedish Research CouncilSwedish Research Council [SNIC 2020/5-146, SNIC 2020/14-17, 2018-05973]; Italian Ministry of Education and Research (MIUR) under the project EleGaNTeMinistry of Education, Universities and Research (MIUR) [PON ARS01_01007]; European Structural and Investment Funds [VEKOP-2.3.3-15-2016-00002]; [VR 2016-05362]</p

Seed-Layer-Free Atomic Layer Deposition of Highly Uniform Al2O3 Thin Films onto Monolayer Epitaxial Graphene on Silicon Carbide

Atomic layer deposition (ALD) is the method of choice to obtain uniform insulating films on graphene for device applications. Owing to the lack of out-of-plane bonds in the sp(2) lattice of graphene, nucleation of ALD layers is typically promoted by functionalization treatments or predeposition of a seed layer, which, in turn, can adversely affect graphene electrical properties. Hence, ALD of dielectrics on graphene without prefunctionalization and seed layers would be highly desirable. In this work, uniform Al2O3 films are obtained by seed-layer-free thermal ALD at 250 degrees C on highly homogeneous monolayer (1L) epitaxial graphene (EG) (amp;gt;98% 1L coverage) grown on on-axis 4H-SiC(0001). The enhanced nucleation behavior on 1L graphene is not related to the SiC substrate, but it is peculiar of the EG/SiC interface. Ab initio calculations show an enhanced adsorption energy for water molecules on highly n-type doped 1L graphene, indicating the high doping of EG induced by the underlying buffer layer as the origin of the excellent Al2O3 nucleation. Nanoscale current mapping by conductive atomic force microscopy shows excellent insulating properties of the Al2O3 thin films on 1L EG, with a breakdown field amp;gt; 8 MV cm(-1). These results will have important impact in graphene device technology.Funding Agencies|FlagERA project GraNitE (Ministero dellIstruzione, Universita e Ricerca (MIUR)) [0001411]; FlagERA project GRIFONE; Hungarian Scientific Research Fund (OTKA) [118914]; "Material Science 2015" (RMA)-program of the Swedish Foundation for Strategic Research (SSF); "Generic Methods and Tools for Production 2014" (GMT)-program of the Swedish Foundation for Strategic Research (SSF)</p

Characterization of Plasma-Induced Damage of Selectively Recessed GaN/InAlN/AlN/GaN Heterostructures Using SiCl4 and SF6

We have investigated an inductively coupled plasma etching recipe using SiCl4 and SF6 with a resulting selectivity >10 for GaN in respect to InAlN. The formation of an etch-resistant layer of AlF3 on InAlN required about 1 min and was noticed by a 4-times-higher initial etch rate on bare InAlN barrier high electron mobility transistors (HEMTs). Comparing devices with and without plasma-treatment below the gate showed no degradation in drain current and gate leakage current for plasma exposure durations shorter than 30s, indicating no plasma-induced damage of the InAlN barrier. Devices etched longer than the required time for the formation of the etch-resistant barrier exhibited a slight decrease in drain current and an increase in gate leakage current which saturated for longer etching-time durations. Finally, we could prove the quality of the recipe by recessing the highly doped 6 nm GaN cap layer of a GaN/InAlN/AlN/GaN heterostructure down to the 2 nm thin InAlN/AlN barrier layer. (C) 2010 The Japan Society of Applied Physic