low temperature deposition of silicon nitride thin films by hot-wire cvd energy postgraduate...
TRANSCRIPT
Low temperature deposition of silicon nitride thin films by hot-wire CVD
Low temperature deposition of silicon nitride thin films by hot-wire CVD
Energy Postgraduate Conference 2013
University of the Western CapeUniversity of the Western Cape
A. Adams and C. J. Arendse
Outline• Introduction
• Experimental Details
• Results
• Conclusion
• Acknowledgments
Introduction• Solar power
– Energy crises– Viable alternative– Amorphous solar cells – Antireflective coating for increased efficiency
• Multitude of uses stemming from stoichiometric tunability– Permeation barrier– Gate insulator in thin film electronics– Passivation of dangling bonds– Antireflective coating
Deposition Method• Current technique of choice is PECVD
– Ion bombardment, resulting in oxidation– Complex (potential difference, plasma source)
• Desired technique of choice is HWCVD– Ease of upscale– Eradicates bombardment (absence of plasma ions)
– Low cost– High deposition rates of > 7 nm/s– Low temperature deposition
Experimental details
Technique Information
Reflectance
· Thickness
· Band Gap
· Refractive index
FTIR
· SiN bonds
· Total bonded H
EDS · N/Si ratio
AFM
· Surface morphology
· Roughness
ERDA· H depth profiling
TOF-HIERD
· N depth profiling
· N/Si ratio
XRD · Phase
• The a-SiN:H thin films were deposited at Tw=1400 °C, Ts = 240 °C, P = 100 µbar, ΦH2 = 20 sccm, ΦSiH4 = 5 sccm and ΦNH3 = 1 – 7 sccm (LOW PARAMETERS)
Results and discussion• Decrease in deposition rate as ΦNH3 is
increased• Competing reaction at the filament
• Decrease in surface roughness as ΦNH3 is increased
• columnar structures decreases
Results and Discussion• Films are uniform• Negligible oxidation occurred in the bulk • Increase in N content as NH3 is increased
• ToF-HIERD and EDS corroborate well
NH3 = 5 sccm
Results and Discussion
Results and discussion• Linear relation between static refractive
index and N content• Direct relation between Tauc band gap
and N content
Conclusion
• High quality a-SiN:H deposited at low processing parameters, suitable for device applications (permeation barrier, Passivation layer)
• Resistant to oxidation• Tuneable refractive index• Corroboration between EDS, ToF-HIERD• Low H content• Silicon rich Films
Future Work• Incorporation in organic PV devices
Acknowledgments
• Financial Support− University of the Western Cape− National Research Foundation (NRF)
• Team‒ A. Adams, Prof. C. Arendse, Dr. T. F. G. Muller, Dr. G. Malgas, Dr. C. Oliphant and
Dr. M. Msimanga.