Design & Fabrication of a High-Voltage Photovoltaic Device

Jennifer FelderNorth Carolina State University

Project Advisor: Chris Kenney

Outline

• Brief Review• Motivation• Unique Features of Design• (Mask) Design• Simulation• Fabrication• Conclusion

A Brief Review

• Photoelectric Effect• Photovoltaic (PV) Effect/Devices

Image courtesy of: http://amazingdata.com/mediadata8/Image/amazing_fun_science_technology_20090729124730244.jpg

Project Motivation

• High-Voltage PV• EXO Experiment Power Source• Unique Features of Device– Wavelength– Temperature– Float-zone Si wafers• Impurities• Cost

Wavelength Matching• Band gap & efficiency• Band gap of Si = 1.12 eV• λ=hc/E 1.12 eV ~ 1100 nm• Solar cells?

Temperature & Efficiency

• η drops 0.1% per °C above 25°C• Ex: If it were 105°F (40.5°C) -1.55%• Liquid Xe• Solar cells?

100 μm

Individual Cell Designs (Mask)

Preliminary Calculations

1. Known Parameters

2. Modeling Equations

3. Calculated Parameters

Mask Design: PV Device• Series Connections• Various Voltages (50-2000 V)• From Calculations:

3 Basic Cell Designs

Simulated

SOI Layer

P Diffusion

N Diffusion

Optimized Cell Design• N-type

diffusion area

• Constraints on area size

Built-in Potential• High built-in potential fewer number cells• Φj ≈ 0.97 V (± 0.01 V between designs)• Not a deciding factor

SRH Recombination

• Low recombination high photovoltage generation

Other Simulation Results

Fabrication

• Stanford Nanofabrication Facility (SNF)• Wet oxidation process– Remove organic materials– Remove metal ions– Oxidation

• Other steps to be finished in future work…

Conclusions

• Feasibility/Proof of Concept Test• Significant Impact– Experiments (EXO)• Noise

– SLAC– Extended to other PV/solar cell technology, many

others!

Acknowledgments

• Chris Kenney• Jasmine Hasi• Astrid Tomada• Julie Segal• DOE• SLAC & SNF Staff

Questions, Comments, Concerns?

Feel free to e-mail me at jkfelder@ncsu.edu