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Title: Temporally and spatially resolved plasma spectroscopy in pulsed laser deposition of ultra-thin boron nitride films

Physical vapor deposition (PVD) has recently been investigated as a viable, alternative growth technique for two-dimensional materials with multiple benefits over other vapor deposition synthesis methods. The high kinetic energies and chemical reactivities of the condensing species formed from PVD processes can facilitate growth over large areas and at reduced substrate temperatures. In this study, chemistry, kinetic energies, time of flight data, and spatial distributions within a PVD plasma plume ablated from a boron nitride (BN) target by a KrF laser at different pressures of nitrogen gas were investigated. Time resolved spectroscopy and wavelength specific imaging were used to identify and track atomic neutral and ionized species including B{sup +}, B*, N{sup +}, N*, and molecular species including N{sub 2}*, N{sub 2}{sup +}, and BN. Formation and decay of these species formed both from ablation of the target and from interactions with the background gas were investigated and provided insights into fundamental growth mechanisms of continuous, amorphous boron nitride thin films. The correlation of the plasma diagnostic results with film chemical composition and thickness uniformity studies helped to identify that a predominant mechanism for BN film formation is condensation surface recombination of boron ions and neutral atomic nitrogen species. Thesemore » species arrive nearly simultaneously to the substrate location, and BN formation occurs microseconds before arrival of majority of N{sup +} ions generated by plume collisions with background molecular nitrogen. The energetic nature and extended dwelling time of incident N{sup +} ions at the substrate location was found to negatively impact resulting BN film stoichiometry and thickness. Growth of stoichiometric films was optimized at enriched concentrations of ionized boron and neutral atomic nitrogen in plasma near the condensation surface, providing few nanometer thick films with 1:1 BN stoichiometry and good thicknesses uniformity over macroscopic areas.« less
Authors:
 [1] ;  [2] ;  [1] ;  [2] ; ;  [1] ;  [2] ;  [3] ;  [1]
  1. Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB, Ohio 45433 (United States)
  2. (United States)
  3. School of Mechanical Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States)
Publication Date:
OSTI Identifier:
22402950
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 16; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; BORON IONS; BORON NITRIDES; CONCENTRATION RATIO; ENERGY BEAM DEPOSITION; KINETIC ENERGY; KRYPTON FLUORIDE LASERS; LASER RADIATION; NITROGEN; NITROGEN IONS; PHYSICAL VAPOR DEPOSITION; PLASMA; PULSED IRRADIATION; SPATIAL DISTRIBUTION; SPECTROSCOPY; SUBSTRATES; THICKNESS; THIN FILMS; TIME RESOLUTION; TIME-OF-FLIGHT METHOD; TWO-DIMENSIONAL SYSTEMS