Advanced Electron-Beam Techniques for Solar Cell Characterization

This dissertation presents a detailed comparative study of advanced electron-beam based techniques for solar cell characterization. Firstly, the advantage of the subsurface imaging of scanning electron acoustic microscopy (SEAM) was utilized to characterize the structural properties of saw-damage-induced defects and the non-destructive nature of SEAM could enable accurate optimization of saw-damage etch process duration. SEAM was also employed together with electron beam induced current (EBIC) to investigate defects in photovoltaic devices. It was found that combination of these two techniques could provide complementary information that clearly distinguishes the morphological and electrical nature of the defects. The first demonstration of single contact EBIC (SCEBIC) on solar cells is then reported and the experimental results were supported with an analytical model and clearly explained using SPICE simulations. The requirement on only one contact enables SCEBIC to be performed on partially processed solar cells, thus allowing a high degree of flexibility of SCEBIC and its potential applications in photovoltaic industry. Lastly, highly localized quantitative EBIC were demonstrated to measure surface recombination velocity (SRV) for solar cells with different surface passivation conditions. A three-dimensional Monte Carlo simulation for electron-beam sample interaction was first employed to create a three-dimensional carrier generation profile for accurate modelling of EBIC using Sentaurus TCAD. These simulation results were then verified using experimental data that were almost perfectly matching, clearly demonstrating the capability and benefit of the high resolution and accuracy of quantitative EBIC for the extraction of SRV for solar cells.

Author dc:creator

• MENG LEI

• scanning electron microscopy, solar cell, characterization, scanning electron acoustic microscopy, electron beam induced current, defect