Growth of metamorphic InGaP for wide-bandgap photovoltaic junction by MBE

John Simon, Stephanie Tomasulo, Paul Simmonds, Manuel Romero, Minjoo L. Lee

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Metamorphic triple-junction solar cells can currently attain efficiencies as high as 41.1%. Using additional junctions could lead to efficiencies above 50%, but require the development of a wide bandgap (2.0-2.2eV) material to act as the top layer. In this work we demonstrate wide bandgap InyGa 1-yP grown on GaAsxP1-x via solid source molecular beam epitaxy. Unoptimized tensile GaAsxP1-x buffers grown on GaAs exhibit asymmetric strain relaxation, along with formation of faceted trenches 100-300 nm deep in the [01-1] direction. Smaller grading step size and higher substrate temperatures minimizes the facet trench density and results in symmetric strain relaxation. In comparison, compressively- strained graded GaAsxP1-x buffers on GaP show nearly-complete strain relaxation of the top layers and no evidence of trenches. We subsequently grew InyGa1-yP layers on the GaAs xP1-x buffers. Photoluminescence and transmission electron microscopy measurements show no indication of phase separation or CuPt ordering. Taken in combination with the low threading dislocation densities obtained, MBE-grown InyGa1-yP layers are promising candidates for future use as the top junction of a multi-junction solar cell.

Original languageEnglish (US)
Title of host publicationDefects in Inorganic Photovoltaic Materials
PublisherMaterials Research Society
Number of pages6
ISBN (Print)9781605112459
StatePublished - 2010
Externally publishedYes

Publication series

NameMaterials Research Society Symposium Proceedings
ISSN (Print)0272-9172

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


Dive into the research topics of 'Growth of metamorphic InGaP for wide-bandgap photovoltaic junction by MBE'. Together they form a unique fingerprint.

Cite this