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Title: Single- and dual-variant atomic ordering in GaAsP compositionally graded buffers on GaP and Si substrates

Journal Article · · Journal of Crystal Growth
ORCiD logo [1];  [2];  [3];  [3];  [3];  [2];  [2];  [2]
  1. National Renewable Energy Lab. (NREL), Golden, CO (United States)
  2. Fraunhofer Institute for Solar Energy Systems ISE, Freiburg (Germany)
  3. Philipps-Univ. Marburg, Marburg (Germany)
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Here, we investigate the material properties of GaAsP graded buffers on both GaP and Si substrates in order to determine limitations to dislocation glide in GaAsP. Phase separation is not observed in these GaAsP buffers, but CuPtB atomic ordering is present, and has an impact on the Burgers vector distribution of gliding dislocations. Tellurium surfactant eliminates ordering in GaAsP, allowing control over the glide plane distribution while highlighting the importance of the growth surface and choice of dopant. The impact of single-variant CuPtB ordering of GaAsP buffers grown on GaP substrates is investigated by monitoring the threading dislocation density throughout the buffer in sequential steps. The dislocation density rises steadily throughout the graded buffer, implying that factors other than ordering-induced glide plane switches play a dominant role in the final dislocation density. We observe an increase in surface roughness throughout the buffer and speculate that a dislocation nucleation source on the surface has a low activation energy and may lead to increased threading dislocation density. On Si substrates, the GaAsP buffer displays dual-variant CuPtB ordering rather than single-variant ordering due to the surface step geometry. We discuss how dual-variant ordering leads to a variable glide force, and thus has a different impact on dislocation dynamics than single-variant ordering. Because the III-V on Si nucleation procedure determines the step geometry, it also influences the dislocation dynamics.

Research Organization:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Organization:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Renewable Power Office. Solar Energy Technologies Office
Grant/Contract Number:
AC36-08GO28308
OSTI ID:
1476977
Alternate ID(s):
OSTI ID: 1635917
Report Number(s):
NREL/JA-5900-71922
Journal Information:
Journal of Crystal Growth, Vol. 506, Issue C; ISSN 0022-0248
Publisher:
ElsevierCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 5 works
Citation information provided by
Web of Science

Figures / Tables (9)

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