Defects in Epitaxial Lift-Off Thin Si Films/Wafers and Their Influence on the Solar Cell Performance

Helio Moutinho, Robert Reedy Jr., Kaitlyn VanSant, Somnath Nag, T.S. Ravi, Jean Vatus, Ruiying Hao

Research output: Contribution to conferencePaper


In this paper, we will describe the nature of defects and impurities in thick epitaxial-Si layers and their influence on the cell efficiency. These wafers have very low average dislocation density. Stacking faults (SFs) are the main defect in epi layers. They can occur in many configurations - be isolated, intersecting, and nested. When nested, they can be accompanied by formation of coherent twins resulting in dendritic growth, with pyramids protruding out of the wafer surface. Such pyramids create large local stresses and punch out dislocations. The main mechanism of dislocation formation is through pyramids. Stacking faults degrade solar cell performance. Analyses of the solar cells have revealed that the nested SFs have a controlling effect on the solar cell performance. A well-controlled growth can minimize defect generation and produce wafers that can yield cell efficiencies close to 20%.
Original languageAmerican English
Number of pages6
StatePublished - 2014
EventMaterials Research Society Spring Meeting - San Francisco, California
Duration: 21 Apr 201425 Apr 2014


ConferenceMaterials Research Society Spring Meeting
CitySan Francisco, California

NREL Publication Number

  • NREL/CP-5J00-60693


  • crystal defects
  • epitaxial
  • silicon
  • solar cells


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