Light emission in Si avalanches

For about half a century, light emission observed in Si avalanches has been a well-known process. In numerous measurements the researchers measured its intensity and spectrum shape, but unfortunately still there are non-negligible differences between measurements. Recently the interest in this effect has been revived because of the SiPM (GAPD, MPPC, micro-channel APD). One of the main drawbacks of SiPM is due to the light emission in avalanches that causes a cross-talk between neighbour cells. In many applications this can strongly degrade the performance of SiPM. We measured the light emitted by a 1 mm×1 mm Hamamatsu MPPC that was coupled to a spectrograph. We report here our measurements of the differential light emission in the wavelength range 450–1600 nm. The measurements were made using CCDs sensitive to visible and near-infrared light.