13-04-2012, 11:01 AM
EE198B
[attachment=20045]
Project Objective
To design, simulate, establish and document a silicon process base-line traveler for the Single Crystal Solar Photocell.
To enhance the relative efficiency of the Solar Photocells by 5%.
Fabrication of Solar Cells
Diffuse donor region
Apply aluminum coating to front of wafer
Photolithography to define solar cell pattern
Etch aluminum to create solar cell pattern
Apply anti-reflection coating *
Apply aluminum coating to back of wafer
Anneal wafers
Remove outer edges of wafers
Diffuse Donor Region
Spin on phosphorous doped silica glass
Apply 3ml to front of wafer
Spin @ 3000 rpm for 20 seconds
Diffuse in furnace
Heat furnace to 1100oc
Push in wafers ½ inch per 15 seconds
Diffuse for 1 hour
Pull out wafers ½ inch per 15 seconds
Makes wafer into a large diode
Photolithography
Apply 3ml photo-resist; Spin for 20s @ 5000 rpm
Soft bake for 90oc for 30 minutes
Place solar cell mask on wafer
Place both into wooden and glass holder
Expose under lamp for 2 minutes
Develop for 15 seconds
Testing the Solar Cells
Scored, or roughened, back of cells
Placed onto roughened aluminum wafer
Used probes to make contacts
One probe onto the corner of the cell’s al grid
One probe onto the al wafer
Tried various methods for making good contacts
Solder paste
Silver paste
Copper tape
Conclusions
AR cells average of 17.8% more efficient
Efficiency increase = (PmaxOLD – PmaxAR)/PmaxOLD
Wanted minimum 5% increase
Easy to follow process
Recommendations
Use the smaller grid
Possible photolithography and etch of back al
[attachment=20045]
Project Objective
To design, simulate, establish and document a silicon process base-line traveler for the Single Crystal Solar Photocell.
To enhance the relative efficiency of the Solar Photocells by 5%.
Fabrication of Solar Cells
Diffuse donor region
Apply aluminum coating to front of wafer
Photolithography to define solar cell pattern
Etch aluminum to create solar cell pattern
Apply anti-reflection coating *
Apply aluminum coating to back of wafer
Anneal wafers
Remove outer edges of wafers
Diffuse Donor Region
Spin on phosphorous doped silica glass
Apply 3ml to front of wafer
Spin @ 3000 rpm for 20 seconds
Diffuse in furnace
Heat furnace to 1100oc
Push in wafers ½ inch per 15 seconds
Diffuse for 1 hour
Pull out wafers ½ inch per 15 seconds
Makes wafer into a large diode
Photolithography
Apply 3ml photo-resist; Spin for 20s @ 5000 rpm
Soft bake for 90oc for 30 minutes
Place solar cell mask on wafer
Place both into wooden and glass holder
Expose under lamp for 2 minutes
Develop for 15 seconds
Testing the Solar Cells
Scored, or roughened, back of cells
Placed onto roughened aluminum wafer
Used probes to make contacts
One probe onto the corner of the cell’s al grid
One probe onto the al wafer
Tried various methods for making good contacts
Solder paste
Silver paste
Copper tape
Conclusions
AR cells average of 17.8% more efficient
Efficiency increase = (PmaxOLD – PmaxAR)/PmaxOLD
Wanted minimum 5% increase
Easy to follow process
Recommendations
Use the smaller grid
Possible photolithography and etch of back al