Investigation of the microstructure and optical properties of hydrogenated polymorphous silicon films prepared with pure silane

Abstract

The dependences of microstructure and optical properties of hydrogenated polymorphous silicon (pm-Si:H) films on total gas pressure were studied. Instead of using high diluted silane in H₂, pure silane was used as the source gas. The films were grown by the radio-frequency plasma-enhanced chemical vapour deposition method. Fourier-transform infrared spectrometry was used to characterize the presence of Si _m H _n clusters in pm-Si:H film deposited on KBr substrate. Atomic force microscopy (AFM) analysis characterized the morphology of the pm-Si:H films and X-ray diffraction at grazing incidence angle (XRDGI) microstructure analysis also confirmed the existence of Si _m H _n nanocrystalline clusters in pm-Si:H. The thickness and optical constants of the films were measured by spectra ellipsometry as well as scanning electron microscopy. Derived using the Tauc relation, the dependence of optical bandgap, E_g , and coefficient, B, on the pressure during deposition process is discussed. The influence of inter-electrode distance on growth rate and surface smooth was analyzed using AFM.

Acknowledgement

This work was partially supported by the New Century Education Talent of China Ministry of Education through grant No. NCET-04-0896.