Imaging of spatial non-uniformities and the characterization of defects in photovoltaic devices using a LASER-beam-induced-current (LBIC) mapping technique.

摘要

Imaging of electrical defects in photovoltaic (PV) devices can provide detailed information for the analysis and characterization of such devices and processing techniques. Spatial non-uniformities introduced during device processing and handling can be located and investigated using a LASER-beam-induced-current (LBIC) mapping technique. An LBIC imaging system utilizing a scanning LASER beam and fixed sample location has been built at the University of Delaware's Institute of Energy Conversion in an effort to locate and analyze spatial non-uniformities. The incident LASER beam, focused to 26 um (edge-to-edge), is translated across a stationary sample using computer-controlled beam deflection mirrors. Developed software routines allow for an effective imaging resolution (∼10um) through the rapid averaging of data points. A typical scan of ∼5 cm^2, with a resolution of ∼15um, can be created in approximately 40 minutes.This system has the ability to image large area PV devices (Area 1 m^2)as well as small area defects (Area 100 um^2), and has been used to detectdefects in photovoltaic devices ranging from c-Si & mc-Si to thin film devices based on CdTe- and Cu(In[1-x] Ga[x])Se2-.