Impacts of Mode Mixity on Controlled Spalling of (100)-Oriented Germanium

Corinne Packard, Jie Chen, Jason Chenenko

Research output: Contribution to journalArticlepeer-review

2 Scopus Citations


Controlled spalling is a technology to prepare single-crystal thin films of semiconductors by fracture with a subsurface crack propagating nearly parallel to the substrate surface. Practical applications require uniform thickness and a smooth surface across the whole film. Both wafer-scale and patterned-stressor-defined small-area spalling of germanium substrates are conducted experimentally and numerically. River line features are observed on spalled surfaces close to lateral edges of the spall, regardless of the spall direction and the size of the spalled area. Three-dimensional finite element method modeling shows the river lines are caused by mixed mode I?+?III loading near the lateral edges of spall and predicts a spall depth variation near the lateral edges of spall due to mixed mode I?+?II loading. The absolute range of river lines increases with lateral size of spall, while the relative range of river lines decreases, consistent with variations in mode mixity.
Original languageAmerican English
Pages (from-to)1607-1616
Number of pages10
Issue number6
StatePublished - 2021

NREL Publication Number

  • NREL/JA-5900-78868


  • controlled spalling
  • crack propagation
  • Ge wafers
  • germanium wafers
  • mode III loading
  • photovoltaic
  • PV
  • river lines
  • twist hackles


Dive into the research topics of 'Impacts of Mode Mixity on Controlled Spalling of (100)-Oriented Germanium'. Together they form a unique fingerprint.

Cite this