Applications of laser annealing and laser-induced diffusion to photovoltaic conversion

Conference · Tue Jan 01 04:00:00 EST 1980

OSTI ID:7088947

Young, R. T.; Lowndes, D. H.; Wood, R. F.

Progress in the development of polycrystalline solar cells is hampered by the present poor state of knowledge about electronic and ionic processes at grain boundaries. A major difficulty in studying such processes is that conventional growth and thermal diffusion techniques used for doping semiconductors cause segregation of the dopant at grain boundaries and are unable to provide control of the fast diffusion which is known to occur along grain boundaries. The salient features of two new techniques for the study and control of grain boundary effects are reviewed. Neutron transmutation doping is a method for circumventing segregation problems in bulk polycrystalline silicon. With such doping, long-range diffusion does not occur in the material and hence the dopants cannot migrate to grain boundaries. Laser annealing and laser-induced diffusion are two other newly developed techniques which can be used to control grain boundary diffusion and segregation. With these techniques, the near-surface region of a sample actually melts but stays molten for such a short time (approx. 10/sup -7/ sec) that significant dopant migration cannot occur. These new doping methods do not necessarily insure better efficiencies of cells made from polycrystalline materials, but they provide a degree of control of dopants that has not been available before and hence make possible more definitive studies of grain boundary effects. Laser techniques can also be used to promote growth, and evidence from EBIC and TEM indicates that pulsed-laser annealing changes the elementary structure of some types of grain boundaries. Also, efforts to understand the role of lithium in polycrystalline Si are described. (WHK)

• Research Organization: Oak Ridge National Lab., TN (USA)
• Sponsoring Organization: USDOE Division of Materials Science
• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 7088947
• Report Number(s): CONF-801153--1
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140501* -- Solar Energy Conversion-- Photovoltaic Conversion
ALLOYS
ANNEALING
BARYON REACTIONS
CRYSTAL DOPING
CRYSTAL STRUCTURE
CRYSTALS
DIFFUSION
DIRECT ENERGY CONVERTERS
EQUIPMENT
GRAIN BOUNDARIES
HADRON REACTIONS
HEAT TREATMENTS
HEATING
LASER-RADIATION HEATING
LITHIUM ADDITIONS
LITHIUM ALLOYS
MICROSTRUCTURE
NEUTRON REACTIONS
NUCLEAR REACTIONS
NUCLEON REACTIONS
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
PLASMA HEATING
POLYCRYSTALS
RESEARCH PROGRAMS
SILICON SOLAR CELLS
SOLAR CELLS
SOLAR EQUIPMENT
TRANSMUTATION
TRAPPING