Application of Photon Emission Microscopy (PEM) in semiconductor characterization often shows a linear dependence between emission intensity and biasing current. However, inconclusive understanding of photon emission phenomena in Silicon stopped the research community form applying PEM for local current estimation. In this paper we show for the first time that the linear relationship is valid for avalanche breakdown in the range of currents across five orders of magnitude. And we conclude that the observed relationship is independent of non-radiative effects. Using the observed photon emission pattern we perform a detailed analysis of the influence of the junction geometry and doping topology on the breakdown phenomenon. We also for the first time estimate the local I-V curves in the junction and demonstrate the complexity of the breakdown phenomenon. Our results also demonstrate a poor applicability of global I-V curve measurements for calibration of existing TCAD models.