Phonon-Enhanced Crystal Growth and Lattice Healing

Technology #13974

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FIGS. 2A-2C are schematic diagrams and a SEM diagram illustrating the arrangement and performance of the invention;FIG. 3 is a table illustrating the properties of Si phonons formed in accordance with the inventionFIG. 4 is a table illustrating the properties of acoustical phonons formed in accordance with the invention
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Inventors
Professor Anthony Buonassisi
Department of Mechanical Engineering, MIT
External Link (pv.mit.edu)
Mariana Bertoni
Laboratory for Manufacturing and Productivity, MIT
Bonna Newman
Laboratory for Manufacturing and Productivity, MIT
Managed By
Christopher Noble
MIT Technology Licensing Officer - Clean and Renewable Energy
Patent Protection

Phonon-Enhanced Crystal Growth and Lattice Healing:

US Patent 8,450,704

Applications

This technology reduces defect concentration and increases the photovoltaic efficiency of polycrystalline silicon and other semiconductors.

Problem Addressed

Defects within semiconductor crystal lattices can reduce PV efficiency, and producing single-crystal wafers and blocks is expensive and slow.  This technology significantly boosts the performance of cheaper polycrystalline cells without significantly increasing costs.

Technology

Defects within the crystal lattice reduce carrier lifetimes so high defect concentrations can reduce semiconductor device performance.  This is the case for photovoltaic cells.  However, due to the high cost of single-crystal silicon, the efficiency of the solar cells are often sacrificed to reduce costs.  This technology improves the performance of cheaper polycrystalline semiconductors through dislocation annihilation.  Thermal, acoustic, or optical excitation of the wafer or block at the phonon frequencies create atomic-level waves within the material.  The waves move dislocations toward each other so they can recombine or toward the surface of the material where they have less impact on device performance.  This treatment significantly reduces defect concentrations so the performance of polycrystalline semiconductors becomes comparable to high-quality monocrystalline materials.

Advantages

  • Improves performance of polycrystalline silicon and other semiconductors
  • Compatible with current PV manufacturing processes