Molecular beam epitaxy of metamorphic InyGa1-yP solar cells on mixed anion GaAsx P1-x/GaAs graded buffers

Stephanie Tomasulo, John Simon, Paul J. Simmonds, Jonathan Biagiotti, Minjoo L. Lee

Research output: Contribution to journalArticlepeer-review


The authors have grown metamorphic InyGa1-yP on optimized GaAsx P1-x/GaAs graded buffers via solid source molecular beam epitaxy (MBE) for multijunction solar cell applications. In this work, the authors show that a previously developed kinetic growth model can be used to predict the composition of mixed anion GaAsx P1-x alloys on GaAs as a function of substrate temperature and group-V flux. The advantages of using a high growth temperature of 700°C are then described, including the minimized dependence of composition on small temperature variations, a linear dependence of film composition on incident group-V flux ratio, and the ability to attain low threading dislocation densities of ≤ 106 cm-2. The authors then discuss the effect of faceted trenches, a morphological defect specific to tensile strain relaxation, on minority carrier properties, as well as strategies to eliminate them. Growth temperature effects, phase separation, and difficulties encountered in n -type doping of InAlP:Si are then described in the context of Iny Ga 1-yP solar cell growth. The MBE growth techniques presented here have enabled the demonstration of 2.00 eV band gap metamorphic In0.39 Ga0.61P solar cells, exhibiting open-circuit voltages as high as 1.42 V. These results indicate that metamorphic Iny Ga1-yP is a promising material for future multijunction solar cells.

Original languageEnglish (US)
Article number03C118
JournalJournal of Vacuum Science and Technology B:Nanotechnology and Microelectronics
Issue number3
StatePublished - May 2011
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Instrumentation
  • Process Chemistry and Technology
  • Surfaces, Coatings and Films
  • Electrical and Electronic Engineering
  • Materials Chemistry


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