Infrared semiconductor laser crystallization of silicon thin films using diamond-like carbon as photoabsorption layer

We report the crystallization of silicon thin films using a continuous wave (CW) infrared semiconductor laser with the assistance of diamond-like carbon (DLC) as a photoabsorption layer. A beam of a 940-nm-wavelength CW semiconductor laser was irradiated to samples of 400-nm-thick DLC/50-nm-thick Si/glass with a laser power density of 7.4-24.7 kW/cm(2). The beam was scanned on the samples at a speed of 15-100cm/s. The DLC layer was heated to a temperature above the melting point of silicon by effective absorption of laser light. Thus, the underlying 50-nm-thick silicon films were crystallized by the heat defused from DLC. It was found that the threshold energy density for the crystallization of silicon films decreased as the laser power density increased. The maximum crystallinity factors estimated from Raman scattering spectral data of silicon films were 1 and 0.78 for laser power densities of 24.7 and 7.8kW/cm(2), respectively. Electron backscattering diffraction pattern (EBSD) measurements revealed that crystalline grains were randomly oriented with an average size of 3 mu m.