Development of an In-Line Minority-Carrier Lifetime Monitoring Tool for Process Control during Fabrication of Crystalline Silicon Solar Cells: Annual Subcontract Report, June 2003 (Revised);

George Mooney, David Mooney (NREL Technical Monitor)

Research output: NRELSubcontract Report

Abstract

Under the PV Manufacturing R&D subcontract 'Development of an In-Line, Minority-Carrier Lifetime Monitoring Tool for Process Control during Fabrication of Crystalline Silicon Solar Cells', Sinton Consulting developed prototypes for several new instruments for use in the manufacture of silicon solar cells. These instruments are based on two families of R&D instruments that were previouslyavailable, an illumination vs. open-circuit-voltage technique and the quasi-steady state RF photoconductance technique for measuring minority-carrier lifetime. Compared to the previous instruments, the new prototypes are about 20 times faster per measurement, and have automated data analysis that does not require user intervention even when confronted by challenging cases. For example,un-passivated multi-crystalline wafers with large variations in lifetime and trapping behavior can be measured sequentially without error. Five instruments have been prototyped in this project to date, including a block tester for evaluating cast or HEM silicon blocks, a CZ ingot tester, an FZ boule tester for use with long-lifetime silicon, and an in-line sample head for measuring wafers. TheCZ ingot tester and the FZ boule tester are already being used within industry and there is interest in the other prototypes. For each instrument, substantial R&D work was required in developing the device physics and analysis as well as for the hardware. This work has been documented in a series of application notes and conference publications, and will result in significant improvements forboth the R&D and the industrial types of instruments.
Original languageAmerican English
Number of pages28
StatePublished - 2004

Bibliographical note

Work performed by Sinton Consulting, Inc., Boulder, Colorado

NREL Publication Number

  • NREL/SR-520-35884

Keywords

  • crystalline silicon (x-Si) (c-Si)
  • float zone (FZ)
  • manufacturing
  • minority carriers
  • open-circuit voltages
  • phosphorus diffusion
  • photoconductance
  • process control
  • PV
  • quasi steady state
  • silicon (Si)
  • solar cells
  • thin films

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