skip to main content

Title: Elimination of carbon vacancies in 4H-SiC employing thermodynamic equilibrium conditions at moderate temperatures

The carbon vacancy (V{sub C}) is a major point defect in high-purity 4H-SiC epitaxial layers limiting the minority charge carrier lifetime. In layers grown by chemical vapor deposition techniques, the V{sub C} concentration is typically in the range of 10{sup 12 }cm{sup −3}, and after device processing at temperatures approaching 2000 °C, it can be enhanced by several orders of magnitude. In the present study, both as-grown layers and a high-temperature processed one have been annealed at 1500 °C and the V{sub C} concentration is demonstrated to be strongly reduced, exhibiting a value of only a few times 10{sup 11 }cm{sup −3} as determined by deep-level transient spectroscopy measurements. The value is reached already after annealing times on the order of 1 h and is evidenced to reflect thermodynamic equilibrium under C-rich ambient conditions. The physical processes controlling the kinetics for establishment of the V{sub C} equilibrium are estimated to have an activation energy below ∼3 eV and both in-diffusion of carbon interstitials and out-diffusion of V{sub C}'s are discussed as candidates. This concept of V{sub C} elimination is flexible and readily integrated in a materials and device processing sequence.
Authors:
;  [1] ;  [2] ;  [3]
  1. University of Oslo, Department of Physics/Center for Materials Science and Nanotechnology, P.O. Box 1048 Blindern, N-0316 Oslo (Norway)
  2. Consiglio Nazionale delle Ricerche, Istituto di Microelettronica e Microsistemi, Sezione di Bologna (CNR-IMM of Bologna), I-40129 Bologna (Italy)
  3. Royal Institute of Technology, School of Information and Communication Technology (ICT), SE-164 40 Kista-Stockholm (Sweden)
Publication Date:
OSTI Identifier:
22486269
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 107; Journal Issue: 25; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ACTIVATION ENERGY; ANNEALING; CARBON; CHARGE CARRIERS; CHEMICAL VAPOR DEPOSITION; DEEP LEVEL TRANSIENT SPECTROSCOPY; DIFFUSION; EPITAXY; EQUILIBRIUM; EV RANGE; IMPURITIES; INTERSTITIALS; LAYERS; PROCESSING; SILICON CARBIDES; TEMPERATURE RANGE 1000-4000 K; VACANCIES