Objective: Herein, we report the effect of variation of hydrogen flow rate on the
properties of Si:H films synthesized using PE-CVD method. Raman spectroscopy analysis
show an increase in crystalline volume fraction and crystallite size implying that hydrogen
flow in PE-CVD promotes the growth of crystallinity in nc-Si:H films with an expense of a
reduction in deposition rate.
Methods: FTIR spectroscopy analysis indicates that hydrogen content in the film increases
with an increase in hydrogen flow rate and hydrogen is predominantly incorporated in Si-H2
and (Si-H2)n bonding configuration. The optical band gap determined using E04 method and
Tauc method (ETauc) show an increasing trend with an increase in hydrogen flow rate and E04
is found higher than ETauc over the entire range of hydrogen flow rate studied.
Results and Conclusion: We found that the defect density and Urbach energy increases with
an increase in hydrogen flow rate. Photosensitivity (σPhoto /σDark) decreases from ∼103 to ∼1
when hydrogen flow rate is increased from 30 sccm to 100 sccm and can be attributed to
amorphous-to-nanocrystallization transition in Si:H films. The results obtained from the present
study demonstrated that hydrogen flow rate is an important deposition parameter in PECVD
to synthesize nc-Si:H films.
Keywords: Amorphous-to-nanocrystalline transition, Raman Scattering, FTIR spectroscopy, UV-Visible
spectroscopy, Electrical properties, silicon thin films.
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