1. Energy Postgraduate Conference 2013
Low temperature deposition of silicon nitride thin films by hot-wire CVD
University of the Western Cape
A. Adams and C. J. Arendse
Energy Postgraduate Conference 2013

2. Outline Introduction Experimental Details Results Conclusion
Acknowledgments

3. 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

4. Experimental details
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)
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
XRD
·         Phase

5. Results and discussion
Decrease in surface roughness as ΦNH3 is increased
columnar structures decreases
Decrease in deposition rate as ΦNH3 is increased
Competing reaction at the filament

6. 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

7. Results and Discussion

8. Results and discussion
Linear relation between static refractive index and N content
Direct relation between Tauc band gap and N content

9. Conclusion Future Work
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

10. Acknowledgments Financial Support Team 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.