Technical Study On Infrared Pectroscopy Scanning Of Photocarrier Radiometry For Solar Cell

Recently, photovoltaic energy requirements are more increased in the Global world.However the fabrication process of solar cell is too complicated to easily generate thedefect which leads to reduce the optoelectronic conversion efficiency of photovoltaicdevices. Therefore, a reliable nondestructive diagnoiss technique is necessary to monitorthe quality of solar cell. Lasr-induced photocarrier radiometry (PCR) which has theadvantages of non-contactive, nondestructive, and high resolution, it has proven to be asa new technique for nondestructive evaluation (NDE) of semiconductors/optoelectronicdevices. In this work, the minority carrier (electron-hole pair) transport process wasinvestigated, and an analytical solution of minority carrier density wave by modulatedlaser excitation was obtained through Fourier transform and Green function method.PCR experimental apparatus was developed, and it was used to experimentallyinvestigate on PCR infrared spectroscopy scanning for silicon wafer, monocrystallinesilicon (C-Si)/multicrystalline silicon (mc-Si) solar cells.Fristly, the minority carrier transport process was introduced and briefly analyzed,and then the1D carrier density wave models of bipolar semiconductor and solar cellwere developed under modulated laser-indued carrier source. The computer simulationsof PCR frequency responses were carried out to analyze the effects of carrier transportparameters (minority carrier lifetime, diffusion coefficient, and two surfacerecombination velocities) for semiconductor and solar cell.Secondly, the PCR frequency response and scan imaging systems were established,and the in-house softwares of Labview were developed to the PCR signal acquisitionand analysis. The system responsable stability was validated by different light intensityresponse measurment.Finally, the PCR frequency responses and scan imagings experiments wereconducted to silicon wafer and C-Si/mc-Si solar cells. The carrier transport parameterswere obtained by best-fit multi-parameters. The minority carrier lifetime of Si wafer issimilar to the quasi-steady photoconductance measurement. The carrier transportproperties of C-Si solar cell which was damaged by egergy particles irradiation werestudied. In additional, the inhomogenous carrier transport properties of mc-Si solar cellwere analyized by using PCR technique.