Applications of DMD-based Inhomogeneous Illumination Photoluminescence Imaging for Silicon Wafers and Solar Cells

Under inhomogeneous illumination, a silicon wafer or solar cell can generate lateral current flow due to gradients in the quasi Fermi energy levels. This lateral current flow is impacted by a few of the key electrical parameters of the sample, such as emitter sheet resistance, series resistance and diffusion length. This lateral current flow can be directly correlated to the spatially resolved luminescence intensity from the photoluminescence image. Therefore, photoluminescence imaging with inhomogeneous illumination can provide additional information, which is usually difficult to extract from a conventional photoluminescence image at open circuit voltage.