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Title: Calcium impurity as a source of non-radiative recombination in (In,Ga)N layers grown by molecular beam epitaxy

Ca as an unintentional impurity has been investigated in III-nitride layers grown by molecular beam epitaxy (MBE). It has been found that Ca originates from the substrate surface, even if careful cleaning and rinsing procedures are applied. The initial Ca surface coverage is ~10 12 cm -2, which is consistent with previous reports on GaAs and silicon wafers. At the onset of growth, the Ca species segregates at the growth front while incorporating at low levels. The incorporation rate is strongly temperature dependent. It is about 0.03% at 820 °C and increases by two orders of magnitude when the temperature is reduced to 600 °C, which is the typical growth temperature for InGaN alloy. Consequently, [Ca] is as high as 10 18 cm -3 in InGaN/GaN quantum well structures. Such a huge concentration might be detrimental for the efficiency of light emitting diodes (LEDs) if one considers that Ca is potentially a source of Shockley-Read-Hall (SRH) defects. We thus developed a specific growth strategy to reduce [Ca] in the MBE grown LEDs, which consisted of burying Ca in a low temperature InGaN/GaN superlattice (SL) before the growth of the active region. Finally, two LED samples with and without an SLmore » were fabricated. An increase in the output power by one order of magnitude was achieved when Ca was reduced in the LED active region, providing evidence for the role of Ca in the SRH recombination.« less
Authors:
 [1] ; ORCiD logo [2] ;  [1] ;  [1]
  1. Univ. of California, Santa Barbara, CA (United States). Materials Dept.
  2. Univ. of California, Santa Barbara, CA (United States). Materials Dept.; Swiss Federal Inst. of Technology (EPFL), Lausanne (Switzerland). Inst. of Physics
Publication Date:
Grant/Contract Number:
EE0007096
Type:
Accepted Manuscript
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 109; Journal Issue: 21; Journal ID: ISSN 0003-6951
Publisher:
American Institute of Physics (AIP)
Research Org:
Univ. of California, Santa Barbara, CA (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Building Technologies Office (EE-5B); King Abdulaziz City for Science and Technology, Riyadh (Saudi Arabia); King Abdullah Univ. of Science and Technology, Thuwal (Saudi Arabia)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Condensed matter properties; Mass spectrometry; Light emitting diodes; Surface and interface chemistry; Chemical analysis; Semiconductors; III-V semiconductors; Quantum wells; Surface treatments; Thin film deposition
OSTI Identifier:
1429096
Alternate Identifier(s):
OSTI ID: 1333348