IR absorption property in nano-thick nickel silicides

We fabricated thermaly evaporated 10 nmNi/(poly)Si films to investigate the energy saving property of silicides formed by rapid thermal annealing (RTA) at the temperature of 300-1200°C for 40 seconds. Moreover, we fabricated 10-50 nm-thick ITO/Si films with a rf-sputter as reference films. A four-point tester was used to investigate the sheet resistance. A transmission electron microscope (TEM) and an X-ray diffractometer were used for the determination of cross sectional microstructure and phase changes. A UV-VIS-NIR and FT-IR (Fourier transform infrared rays spectroscopy) were employed for near-IR and middle-IR absorbance. Through TEM analysis, we confirmed 20-70 nm-thick silicide layers formed on the single and polycrystalline silicon substrates. Nickel silicides and ITO films on the single silicon substrates showed almost similar absorbance in near-IR region, while nickel silicides on polycrystalline silicon substrate showed superior absorbance above 850 nm near-IR region to ITO films. Nickel silicide on polycrystalline substrate also showed better absorbance in middle IR region than ITO. Our result implies that nano-thick nickel silicides may have exellent absorbing capacity in near-IR and middle-IR region.