Yumou Chen

Working as a test engineer for solar cells at the Solar Cell Test Laboratory of TW Solar.
I am mainly focusing my experiments and measurements on BC(Back contact) cells, TOPCon(Tunnel Oxide Passivating Contacts) cells, PERC(Passivated Emitter and Rear Cell) cells, and HJT(Heterojunction with Intrinsic Thin-layer) cells.

1. Performing PL-EL (Photoluminescence and Electroluminescence) on the wafer. Analyzing the PL-EL image determines:

-The carrier concentration.

-The carrier lifetime.

-High series resistance.

-The crystal defects include invisible cracks, crystal dislocation, and grain boundaries of polycrystalline.

-The wafer surface contaminations include fingerprints, conveyor belt marks, and scratch marks.

2. Conducting TLM measurements on various solar cell types(Obtain Sheet resistance, Line resistance, Contact resistivity). with a particular focus on addressing the "current crowding effect" to aid the designing team in reshaping busbar geometries and increasing effective contact area by adjusting the "transfer length".

3. Performing Raman spectroscopy and my responsibilities include: -Identify the material by analyzing Anti-Stocks shifts from solar cells including Al3O3, SiNx, Poly-Si, and SiOx layer.

-Helping the production team measure and calculate the crystallization during the PECVD(Plasma Enhanced Chemical Vapor Deposition) process.

-Collaborate with the FEM modeling team to perform Micro-Raman Spectroscopy analysis on BC cells before and after soldering. Determine the stress and strain distribution. The goal is to assist and reduce the experiment time when the module team designs and tests new strings with new materials.

4. Inspect the surface and cross-section of solar cells using a high magnification Scanning Electron Microscope (SEM).

•Surface scanning:

-Examine the surface of the solar cell after the corrosion process (removing the SiNx layer) and check for any silver particles that have penetrated the layer and reached the silicon.

-Busbar and finger area measurement for shading ratio calculation.

•Cross-section:

-various layers(SiNx, AlOx, etc.) thickness measurement.

-Busbar cross-section observation.

-pyramid geometry inspection.

•Perform Energy Dispersive Spectroscopy (EDS) scanning to identify any unknown stains or materials attached to the solar cell. Analyze the potential causes of the stains or marks, such as rust from machinery or pipes in the production line that may be contaminating the solar cell.

5. Using a Spectrophotometer conducting measurements on EVA(Ethylene Vinyl Acetate) and TCO(Transparent Conducting Oxides) film to get the transmittance and reflectance rate.

6. Analyzing the I-V curve and obtaining crucial solar cell characteristics including:

-Voc(open circuit voltage)

-Isc(short circuit current) -FF(fill factor)

-eFF(efficiency)

7. Analyze the quantum efficiency versus wavelength graph for solar cells in different ranges of wavelengths. This analysis will help me identify factors that could affect the efficiency of solar cells, such as how short wavelengths are impacted by the sheet resistance of the solar cell, or how the thickness of TCO or EVA film will affect long-range wavelengths.

8. Performing ECV tests on solar cells. To achieve optimal reliability and efficiency requires precise information on doping profiles. The ECV method can help determine the doping concentration with depth in a solar cell.

• Organizing and determining roles and responsibility for each team member
• Outlining tasks and deadlines for team members in order to complete projects on time
• Communicating with school Labs acquired needed equipment and supplies for project
• Collecting problems and working tight with professor for assistance.
• Prepared PowerPoint for presentation.
• Wrote research paper to summarize how photovoltaic panels works and predictions for future development

• Communicating between Second Harvest Food Bank and San Jose State University student council Organized volunteer event for helping local homeless people.
• Recruiting volunteers through various methods like social media, posters and leaflets.
• Organizing responsibility and roles for 30 volunteers.

• Volunteered for school and sponsored events.
• Participated in event planning and Sponsorship
  negotiation
• Reporting council plans ideas and future events to student body
• Gathering needed materials and equipment for events