WARF: P140041US01

Strain-Tunable Light Emitting Diodes Using Germanium


Max Lagally, Jose Sanchez Perez

The Wisconsin Alumni Research Foundation (WARF) is seeking commercial partners interested in developing tunable PIN diodes that are made of germanium heterojunction layers and can emit radiation over a range of wavelengths.
OVERVIEWGermanium (Ge), a group-IV semiconductor material, is crucial to many established and potential technologies. In optoelectronics, Ge has been used as a photodetector material for on-chip data distribution. This is because it strongly absorbs near-infrared optical communication wavelengths and is compatible with silicon microelectronics. Additional device applications within the emerging field of group-IV photonics (including lasers and solar cells) are being tested as well.
THE INVENTIONUW–Madison researchers have developed new tunable LEDs with germanium PIN heterojunctions. The diodes are made of an undoped (intrinsic) Ge layer between p-type and n-type doped Ge layers. The nano-thin structure can be epitaxially grown and then transferred to a flexible substrate.

Once bonded to the flexible substrate, the whole structure is stretched, causing biaxial tensile strain. Given sufficient strain, the Ge is transformed into a direct-bandgap semiconductor. When voltage is applied, radiation is emitted via electroluminescence. The wavelengths of the emitted radiation can be tuned by adjusting the amount of stretch (i.e., the amount of tensile strain) that is applied.
  • Biological and chemical sensing (e.g., trace gas detection, environmental monitoring, medical diagnostics, industrial process control, etc.)
  • Spectroscopy
  • Secure free-space optical communications
  • More successful than prior germanium-based techniques
  • Wavelengths are emitted in a technologically significant range (1.5 to 2.5 micrometers).
  • Superior emission efficiency
  • New diodes can support population inversion and provide optical gain.
Contact Information
For current licensing status, please contact Jeanine Burmania at or 608-960-9846.
The WARF Advantage

Since its founding in 1925 as the patenting and licensing organization for the University of Wisconsin-Madison, WARF has been working with business and industry to transform university research into products that benefit society. WARF intellectual property managers and licensing staff members are leaders in the field of university-based technology transfer. They are familiar with the intricacies of patenting, have worked with researchers in relevant disciplines, understand industries and markets, and have negotiated innovative licensing strategies to meet the individual needs of business clients.