Optical energy gap measurement of semiconductor ultrathin films using optical waveguides

Naganori Takezawa*, Isamu Kato

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


Measurement of the optical energy gap (Eo) using a slab optical waveguide (SOW) has been studied. With increasing hydrogenated amorphous silicon (a-Si:H) film thickness, transmittance was found to decrease with periodic oscillation. It has been clarified that the oscillation is caused by the change of the field strength distribution of a guided mode in a-Si:H according to the increase of a-Si:H film thickness, using the four-layer structure SOW simulation. By removing the oscillation due to the dependence of transmittance on a-Si:H film thickness, the influence of the oscillation on the values of Eo can be eliminated. As a result, it has been demonstrated that Eo of a-Si:H with thickness on the order of 1/40 that of samples used in the conventional method can be measured. It has been clarified that sufficient absorption to determine Eo of a-Si:H ultrathin films is obtained because the sensitivity of the sensor is increased by changing the size of the SOW.

Original languageEnglish
Pages (from-to)2826-2832
Number of pages7
JournalJapanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers
Issue number5 SUPPL. A
Publication statusPublished - 1996 May


  • a-Si:H
  • Band gap
  • Interference fringe
  • Optical energy gap
  • Slab optical waveguide
  • Ultrathin film

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)
  • Engineering(all)


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