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

Handle URI:
http://hdl.handle.net/10754/623520
Title:
Calcium impurity as a source of non-radiative recombination in (In,Ga)N layers grown by molecular beam epitaxy
Authors:
Young, E. C.; Grandjean, N. ( 0000-0003-3610-981X ) ; Mates, T. E.; Speck, J. S.
Abstract:
Ca as an unintentional impurity has been investigated in III-nitride layers grown by molecular beam epitaxy (MBE). It is found that Ca originates from the substrate surface, even if careful cleaning and rinsing procedures are applied. The initial Ca surface coverage is ∼1012 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 1018 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 SL 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.
Citation:
Young EC, Grandjean N, Mates TE, Speck JS (2016) Calcium impurity as a source of non-radiative recombination in (In,Ga)N layers grown by molecular beam epitaxy. Applied Physics Letters 109: 212103. Available: http://dx.doi.org/10.1063/1.4968586.
Publisher:
AIP Publishing
Journal:
Applied Physics Letters
Issue Date:
23-Nov-2016
DOI:
10.1063/1.4968586
Type:
Article
ISSN:
0003-6951; 1077-3118
Sponsors:
This work was funded in part by the Solid State Lighting Program (SSLP), a collaboration between King Abdulaziz City for Science and Technology (KACST), King Abdullah University of Science and Technology (KAUST), and University of California, Santa Barbara. Additional support for N.G. and J.S. was provided by the DOE Solid State Lighting Program under Award No. DE-EE0007096.
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Publications Acknowledging KAUST Support

Full metadata record

DC FieldValue Language
dc.contributor.authorYoung, E. C.en
dc.contributor.authorGrandjean, N.en
dc.contributor.authorMates, T. E.en
dc.contributor.authorSpeck, J. S.en
dc.date.accessioned2017-05-15T10:35:06Z-
dc.date.available2017-05-15T10:35:06Z-
dc.date.issued2016-11-23en
dc.identifier.citationYoung EC, Grandjean N, Mates TE, Speck JS (2016) Calcium impurity as a source of non-radiative recombination in (In,Ga)N layers grown by molecular beam epitaxy. Applied Physics Letters 109: 212103. Available: http://dx.doi.org/10.1063/1.4968586.en
dc.identifier.issn0003-6951en
dc.identifier.issn1077-3118en
dc.identifier.doi10.1063/1.4968586en
dc.identifier.urihttp://hdl.handle.net/10754/623520-
dc.description.abstractCa as an unintentional impurity has been investigated in III-nitride layers grown by molecular beam epitaxy (MBE). It is found that Ca originates from the substrate surface, even if careful cleaning and rinsing procedures are applied. The initial Ca surface coverage is ∼1012 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 1018 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 SL 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.en
dc.description.sponsorshipThis work was funded in part by the Solid State Lighting Program (SSLP), a collaboration between King Abdulaziz City for Science and Technology (KACST), King Abdullah University of Science and Technology (KAUST), and University of California, Santa Barbara. Additional support for N.G. and J.S. was provided by the DOE Solid State Lighting Program under Award No. DE-EE0007096.en
dc.publisherAIP Publishingen
dc.titleCalcium impurity as a source of non-radiative recombination in (In,Ga)N layers grown by molecular beam epitaxyen
dc.typeArticleen
dc.identifier.journalApplied Physics Lettersen
dc.contributor.institutionMaterials Department, University of California, Santa Barbara, California 93106, USAen
dc.contributor.institutionInstitute of Physics, EPFL, CH-1015 Lausanne, Switzerlanden
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