Organometallic vapor phase epitaxy growth of upright metamorphic multijunction solar cells

X. Q. Liu, C. M. Fetzer, E. Rehder, H. Cotal, S. Mesropian, D. Law, R. R. King

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

We demonstrate an integrated metamorphic AlGaInP/AlGaInAs/GaInAs/Ge 4 J solar cell on Ge substrate using organometallic vapor phase epitaxy (OMVPE). A step graded GaInAs buffer was grown right after the Ge subcell was formed to change the lattice constant from that of Ge to that of Ga 0.8In 0.2As lattice constant followed by a 1.14 eV Ga 0.8In 0.2As subcell, a 1.5 eV (AlGa) 0.8In 0.2As subcell, and a 1.85 eV Al xGa 0.32-xIn 0.68P subcell. Transmission electron microscope (TEM) study shows the threading dislocation density (TDD) is about 6×10 6 cm -2. The X-ray diffraction reciprocal space map (RSM) shows that the structure is 100% relaxed. Bandgap dependent (Al xGa 1-x) 0.32In 0.68P subcell performance is systematically investigated. As the Al xGa 0.32-xIn 0.68P cell bandgap goes up to 1.9 eV, the external quantum efficiency (EQE) goes down significantly. Theoretical simulation shows that the decrease of diffusion length causes the lower EQE, which indicates the material quality degrades with the increasing Al content. Integrated 4 J solar cells are fabricated and characterized with spectral response and tested under the AM1.5D terrestrial spectrum at both 1 sun and 2000 suns.

Original languageEnglish (US)
Pages (from-to)186-189
Number of pages4
JournalJournal of Crystal Growth
Volume352
Issue number1
DOIs
StatePublished - Aug 1 2012
Externally publishedYes

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Keywords

  • A1. X-ray diffraction
  • A3. III-V Materials
  • A3. Metamorphic
  • A3. OMVPE
  • B3. Multijunction solar cells

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Inorganic Chemistry
  • Materials Chemistry

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