Light transmission and internal scattering in pulsed laser-etched partially-transparent silicon wafers

Muhd Hatim Rohaizar, Suhaila Sepeai, Nurfarizza Surhada, N. A. Ludin, M. A. Ibrahim, K. Sopian, Saleem H. Zaidi

Research output: Contribution to journalArticle

Abstract

Continuing trend in silicon wafer thickness directed at cost reduction approaches basic boundaries created by: (a) mismatch between Al paste and Si wafer thermal expansion and (b) incomplete optical absorption. With its symmetrical front and back electrical contacts, the bifacial solar cell setup reduces stress due to mismatch thermal expansion, decreases metal use and increases high temperature efficiency. Efficiency improvement is accomplished in bifacial solar cells by capturing light from the back surface. Partially transparent wafers provide an option to improve near-infrared radiation absorption within Si wafer. To fully absorb optical radiation, three-dimensional texture of these kinds of wafers is essential. Pulsed laser interactions, thermal oxidation, and wet chemical etching are included in this research. A feature of its energy and pattern setup is the interaction of pulsed laser with Si, running at 1.064 μm wavelength and micro-second length. Two experimental settings were explored: (a) post-laser chemical etching with potassium hydro-oxide etching with thermal oxide as etching mask and (b) post-laser heat Si surface oxidation. Due to fast melting and recrystallization, laser pulsed processing inherently produces its own texture. Some of these spherically-shaped, randomly focused characteristics improve inner scattering and boost near-infrared absorption within the wafer. These characteristics are separated during chemical etching with the thermally-grown oxide layer as an etch mask. Comparison of optical absorption in both surfaces shows almost a rise in the magnitude of absorption in non-etched surfaces. Detailed optical (optical microscope and IR absorption), morphological (field emission scanning electron microscope) and heat imaging (far IR camera) analyses were performed to comprehend physical processes that contribute to near-IR absorption improvement. Such kinds of partially-transparent, three-dimensional textured Si wafers are anticipated to discover applications for bifacial solar cells as substrates.

Original languageEnglish
Article numbere02790
JournalHeliyon
Volume5
Issue number11
DOIs
Publication statusPublished - Nov 2019

Fingerprint

light transmission
pulsed lasers
wafers
silicon
etching
scattering
solar cells
oxides
thermal expansion
optical absorption
masks
textures
near infrared radiation
radiation absorption
chemical lasers
heat
oxidation
cost reduction
acceleration (physics)
optical microscopes

Keywords

  • Energy
  • IR transmission
  • Materials characterization
  • Materials physics
  • Nanotechnology
  • Optics
  • Partial transparent
  • Silicon wafer
  • Thermal image
  • Thru-holes
  • Trench

ASJC Scopus subject areas

  • General

Cite this

Light transmission and internal scattering in pulsed laser-etched partially-transparent silicon wafers. / Rohaizar, Muhd Hatim; Sepeai, Suhaila; Surhada, Nurfarizza; Ludin, N. A.; Ibrahim, M. A.; Sopian, K.; Zaidi, Saleem H.

In: Heliyon, Vol. 5, No. 11, e02790, 11.2019.

Research output: Contribution to journalArticle

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