Effects of controllable process factors on Al rear surface bumps in Si solar cells

Sungeun Park, Soohyun Bae, Hyunho Kim, Seongtak Kim, Young Do Kim, Hyomin Park, Soomin Kim, Sung Ju Tark, Chang Sik Son, Donghwan Kim

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

High efficiency solar cells require good back surface field passivation and high back reflectance in the rear Al region. In module processes, wafer-based solar cell can break through stress during soldering uneven rear aluminum surfaces - a serious problem that affects throughput. This work examined rear surfaces with respect to controllable process factors such as ramping and cooling rates during rapid thermal processing, and the fineness of aluminum powder used in the screen-printed paste. A faster ramp up rate resulted in a uniform temperature gradient between the aluminum and silicon surfaces. As a results, the bumps on the aluminum surface were small and of high density. Fine aluminum metal powder in the paste for screen-printing contact points resulted in large distribution, high density bumps. Bumps formed during cooling in metallization, their sizes and densities were dependent the on uniformity of the aluminum and silicon liquid wetting of the silicon surface.

Original languageEnglish
Pages (from-to)17-22
Number of pages6
JournalCurrent Applied Physics
Volume12
Issue number1
DOIs
Publication statusPublished - 2012 Jan

Keywords

  • Al bump
  • Al-Si contact
  • Al-Si eutectic alloy
  • Aluminum back surface field
  • Solar cells

ASJC Scopus subject areas

  • Materials Science(all)
  • Physics and Astronomy(all)

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