Estimation of thermal conductivity of amorphous silicon thin films from the optical reflectivity measurement

Seung Jae Moon, Jung Hyun Choi

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

Amorphous silicon (a-Si) thin film material is widely used in liquid crystal display and solar cell applications. Knowledge of its properties is important in enhancing device performance. The properties of a-Si thin film have not been well understood due to the lack of periodicity of the structure. Furthermore, thermal conductivity of a-Si thin film is a key parameter to understand the complex phase transformation mechanism from a-Si thin film to polysilicon thin film by analyzing the transient temperature during the laser recrystallization process. In this work, thermal conductivity of a-Si thin film was determined by measuring optical reflectivity. A-Si thin film was irradiated with a KrF excimer laser beam to raise its temperature. The raised film temperature affects temperature-dependent optical properties such as refractive indices and extinction coefficients. The temperature-dependent optical properties of refractive indices and extinction coefficients of a-Si thin film were measured by ellipsometry. In-situ transient reflectivity at the wavelength of 633 nm was obtained during the excimer laser irradiation. The numerical simulation of one-dimensional conduction equation was solved so that transient reflectivities were calculated with temperature-dependent optical properties combined with thin film optics. Therefore, a well-fitted thermal conductivity was determined by comparing the numerically obtained transient reflectivity with the experimentally measured reflectivity data. The determined thermal conductivity of a-Si thin films was 1.5 W/mK.

Original languageEnglish
Pages (from-to)6362-6366
Number of pages5
JournalJournal of Nanoscience and Nanotechnology
Volume13
Issue number9
DOIs
StatePublished - Sep 2013

Keywords

  • Amorphous silicon
  • Heat conduction
  • Optical properties
  • Reflectivity
  • Thermal conductivity

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