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Ion Implanted Contacts to Semiconductor Devices

National Renewable Energy Laboratory

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Technology Marketing Summary

To improve solar cell conversion efficiency, researchers have been focused on making improvements to cell contacts in order to decrease the level of carrier recombination at the cell interface. One way to reduce carrier recombination is to passivate the surface of the cell. Surface passivation generally involves either applying another material onto the surface of the cell or doping the silicon wafer, which may be achieved through a variety of means including ion implantation. While ion implantation is advantageous because it allows for the precise control of the depth, uniformity, and number of dopants, overall there remains significant room for improvement in the amount of carrier recombination that occurs at the cell contacts.


Scientists at NREL have developed a way to form low-recombination contacts to semiconductor devices using ion implantation. Here, oxygen ions are implanted into the wafer surface at a desired depth (~60nm), which is followed by implantation of the dopant atoms (e.g. P, As, B, Ga) at a specified depth closer to the surface than the implanted oxygen. The layer is then annealed, creating an intrinsic SiO2 layer at the depth of the oxygen implantation and activating the dopant atoms, ultimately forming doped c-Si region which is ideal for subsequent contacting.

The resulting doped c-Si layer can be further developed through epitaxial growth on the surface to form a high-efficiency tandem solar cell or to provide a surface ideal for low-recombination, ohmic contacts to the wafer. Additionally, metal may be deposited onto the doped c-Si layer to form low resistance contacts.  This method of ion implantation can be especially useful in interdigitated back contact (IBC) cells and is applicable to other devices and materials, beyond c-Si solar cells.

  • Increases solar cell efficiency
  • Low contact resistivity 
  • Applicable to a variety of devices and materials
Applications and Industries
  • Photovoltaic Devices
  • Semiconductor Device Fabrication
  • Metal Finishing
Patents and Patent Applications
ID Number
Title and Abstract
Primary Lab
Application 20170141254
Methods for forming passivated contacts include implanting compound-forming ions into a substrate to about a first depth below a surface of the substrate, and implanting dopant ions into the substrate to about a second depth below the surface. The second depth may be shallower than the first depth. The methods also include annealing the substrate.
National Renewable Energy Laboratory 11/11/2016
Technology Status
Technology IDDevelopment StageAvailabilityPublishedLast Updated
NREL ROI 14-92PrototypeAvailable06/23/201606/23/2016

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To: Bill Hadley<>