Single crystalline boron rich B(Al)N alloys grown by MOVPE
العنوان: | Single crystalline boron rich B(Al)N alloys grown by MOVPE |
---|---|
المؤلفون: | K. Krishnan, N. Y. Sama, Jean-Paul Salvestrini, Phuong Vuong, Gilles Patriarche, Yacine Halfaya, Abdallah Ougazzaden, Paul L. Voss, Simon Gautier, Adama Mballo, Soufiane Karrakchou, Taha Ayari, Suresh Sundaram, Ashutosh Srivastava |
المساهمون: | Georgia Tech Lorraine [Metz], Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Ecole Supérieure d'Electricité - SUPELEC (FRANCE)-Georgia Institute of Technology [Atlanta]-CentraleSupélec-Ecole Nationale Supérieure des Arts et Metiers Metz-Centre National de la Recherche Scientifique (CNRS), Laboratoire de photonique et de nanostructures (LPN), Centre National de la Recherche Scientifique (CNRS), ANR Labex Ganex, LUE, KAUST, ANR-15-IDEX-0004,LUE,Isite LUE(2015), ANR-11-LABX-0014,GANEX,Réseau national sur GaN(2011) |
المصدر: | Applied Physics Letters Applied Physics Letters, American Institute of Physics, 2020, 116 (4), pp.042101. ⟨10.1063/1.5135505⟩ |
بيانات النشر: | HAL CCSD, 2020. |
سنة النشر: | 2020 |
مصطلحات موضوعية: | Materials science, Physics and Astronomy (miscellaneous), Scanning electron microscope, Alloy, Energy-dispersive X-ray spectroscopy, Analytical chemistry, chemistry.chemical_element, Morphology studies, 02 engineering and technology, engineering.material, Epitaxy, 01 natural sciences, [SPI]Engineering Sciences [physics], 0103 physical sciences, Alloys, Metalorganic vapour phase epitaxy, Boron, Wurtzite crystal structure, Energy dispersive X-ray spectroscopy, 010302 applied physics, Optical electronics, 021001 nanoscience & nanotechnology, Secondary ion mass spectroscopy, High resolution X-ray diffraction, chemistry, Transmission electron microscopy, engineering, 0210 nano-technology, Scanning electron microscopy |
الوصف: | International audience; Boron rich BAlN alloys have been grown on 2-inch sapphire substrates by Metal-Organic Vapor Phase Epitaxy. The surface morphology of BAlN alloys exhibits a transition stage from a completely two-dimensional to a three-dimensional granular surface with an increased trimethylaluminum/group III (TMAl/III) ratio. Only a shift in the position of the 002 plane reflection peak to higher diffraction angles in the 2θ−ω scan along with a decrease in intensity was observed, specifying formation of layered BAlN alloys up to a TMAl/III ratio of 14. AlN phase separation was observed while increasing the TMAl/III ratio to 25, supporting SEM observations. Secondary-ion mass spectrometry measurements confirmed the presence of up to 17% Al in layered BAlN alloy systems. A cross sectional transmission electron microscopy (TEM) study confirmed the layered nature of single phase BAlN alloys. It also revealed the presence of wurtzite Al rich BAlN phases in a matrix of layered hexagonal B rich BAlN. Band to band transition around 5.86 eV has been observed, which shifted slightly to lower energy with increasing Al incorporation. The bowing parameter (C) in boron rich BAlN alloy systems was evaluated to be around 0.65 ± 0.05 eV. Encouraging results were obtained on boron rich BAlN alloy formation, motivating further exploration of growth conditions and study of BAlN fundamental properties for applications in deep UV optoelectronics.Hexagonal boron nitride (h-BN) is a unique III-nitride, which has interesting properties such as a layered structure, high thermal conductivity, and a wide bandgap (∼6 eV).1–5 Even though h-BN is an indirect bandgap semiconductor, it has an impressive deep ultraviolet (UV) emission and, hence, it is very promising for applications in deep UV optoelectronics when compared to direct bandgap AlN and other materials.3,6–13 The AlN alloy system, on the other hand, is the most studied material for applications in the deep UV regime, but growth of high quality materials and p-type doping are challenging.6,14 Both Al rich w-BAlN and B rich h-BAlN alloys may enable a desirable bandgap and lattice/strain engineering for applications. For example, h-BN can be made into a direct bandgap material through strain engineering or alloying with Al, which would enhance emission efficiency in the deep UV for UV LEDs. Alloying boron into AlN could also lead to a type II BAlN/AlGaN heterojunction,15 allowing the achievement of an electron blocking layer. BAlN has also been studied as a promising material candidate for high-reflectivity distributed Bragg reflectors (DBRs) due to strong refractive index modification.16,17 Because of their layered nature and reported intrinsic p-type behavior, the use of h-BN based alloys may give more flexibility to design highly efficient device structures.18–20 Theoretically, it was reported that BAlN alloys can have structural crossover from hexagonal to wurtzite at 50% of boron, and the band-gap transition from indirect to direct would occur at 75% of boron.21,22Apart from these theoretical investigations, boron rich BAlN alloys have not yet been explored experimentally. The growth of boron rich BAlN alloys and the understanding of its basic structural, as well as the optical, properties are of high importance. In this work, we report growth of single-phase boron rich BAlN alloys up to 17% of Al in a Metal-Organic Vapor Phase Epitaxy (MOVPE) reactor. We first studied in detail the relationship between morphology, Al composition, and the trimethylaluminum/group III (TMAl/III) ratio. Second, the bandgap variation in boron rich BAlN and the bowing effect were presented.The BAlN alloys were grown directly on c-plane sapphire substrates without any buffer in an Aixtron MOVPE close coupled showerhead (CCS) reactor. Triethylboron (TEB), trimethylaluminum (TMAl), and ammonia (NH3) were precursors for boron, aluminum, and nitrogen, respectively. 20 nm thick of BAlN layers were grown at 1280 °C and 90 mbar pressure. The TMAl/III ratio was varied from 0 to 25; in order to increase the Al content in gas phase, all other parameters were kept constant.A scanning electron microscope (SEM) was used to study the surface morphology of the samples. The crystalline structure and phase purity of BAlN alloys were examined by high-resolution X-ray diffraction (HRXRD) scans, performed in a Panalytical X'pert Pro Materials Research Diffractometers system with Cu Kα radiation in triple axis mode. The aluminum content was estimated by Secondary-ion mass spectrometry (SIMS) using Cs+ molecular ions. The interfaces of heterostructures were characterized by high-angle Annular Dark Field Scanning Transmission electron Microscopy (HAADF-STEM) performed on an aberration-corrected JEOL 2200FS electron transmission microscope. Prior to this study, cross sectional lamellae were prepared by the FIB process after coating a 100 nm thick carbon for layer protection. Transmission spectra were measured at room temperature with a Perkin Elmer LAMBDA 950 spectrophotometer. |
اللغة: | English |
تدمد: | 0003-6951 |
URL الوصول: | https://explore.openaire.eu/search/publication?articleId=doi_dedup___::800edff029541b64556460c4a3c8da19 https://hal.archives-ouvertes.fr/hal-02464319 |
حقوق: | OPEN |
رقم الأكسشن: | edsair.doi.dedup.....800edff029541b64556460c4a3c8da19 |
قاعدة البيانات: | OpenAIRE |
تدمد: | 00036951 |
---|