Applications of laser annealing and laser-induced diffusion to photovoltaic conversion
Over the past several years it has been demonstrated that a variety of techniques involving pulsed laser irradiation of both single crystal and polycrystalline silicon by pulsed lasers can result in the reproducible achievement of high efficiency silicon solar cells. Pulsed laser annealing (PLA) after an ion implantation (II) step results in melting (for a time of order 100 nsec) and essentially defect-free liquid phase epitaxial regrowth within approx. 0.5 ..mu..m of the surface. Complete electrical activation of a number of dopant ions, at concentrations exceeding ordinary solubility limits, has been demonstrated and crystalline (polycrystalline) silicon solar cell efficiencies of 16.6% (12.5%) have been obtained. Other p-n junction and solar cell fabrication techniques have been demonstrated. Pulsed laser processing has also been demonstrated to have several other unique and beneficial advantages in polycrystalline silicon substrates. For example, grain boundaries do not exist during laser melting, while dopant diffusion is taking place; the short melt durations involved further limit dopant diffusion; precipitates present after conventional high temperature dopant diffusion can be removed; and, certain types of electrically active grain boundaries can be made inactive by pulsed laser irradiation. Finally, grain growth in fine-grained polycrystalline silicon films, via pulsed laser melting and recrystallization, has been demonstrated. Because little is known about the application of similar pulsed laser processing techniques to compound semiconductors, particularly in connection with the formation of shallow p-n junctions, research has been devoted to studies of pulsed laser processing of GaAs and compound semiconductor solar cell fabrication techniques that are compatible with the use of pulsed lasers. Progress is reported. (WHK)
- Research Organization:
- Oak Ridge National Lab., TN (USA)
- DOE Contract Number:
- W-7405-ENG-26
- OSTI ID:
- 6552563
- Report Number(s):
- CONF-810349-1
- Resource Relation:
- Conference: High efficiency concentrator and III-V compound contractors in depth review meeting, Raleigh, NC, USA, 31 Mar 1981
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
GALLIUM ARSENIDE SOLAR CELLS
FABRICATION
GALLIUM ARSENIDES
ANNEALING
CRYSTAL DOPING
AMORPHOUS STATE
CRYSTAL DEFECTS
DIFFUSION
EFFICIENCY
ELECTRIC CONTACTS
EPITAXY
GRAIN BOUNDARIES
ION IMPLANTATION
LASER-RADIATION HEATING
MONOCRYSTALS
POLYCRYSTALS
RECRYSTALLIZATION
SILICON
SILICON SOLAR CELLS
SOLAR CELLS
ARSENIC COMPOUNDS
ARSENIDES
CRYSTAL STRUCTURE
CRYSTALS
DIRECT ENERGY CONVERTERS
ELECTRICAL EQUIPMENT
ELEMENTS
EQUIPMENT
GALLIUM COMPOUNDS
HEAT TREATMENTS
HEATING
MICROSTRUCTURE
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
PLASMA HEATING
PNICTIDES
SEMIMETALS
SOLAR EQUIPMENT
140501* - Solar Energy Conversion- Photovoltaic Conversion
360601 - Other Materials- Preparation & Manufacture