Laser-Induced Damage to Silicon Photosensor Arrays

Abstract

Laser-induced damage in two types of silicon photosensor array has been studied. The samples were MOS CCD time delay integration (TDI) sensors with a 2048×96 element array of pixels and CID photodiode arrays of 512×1 pixels. The laser source was a Q-switched 1064 nm Nd:YAG laser (10 Hz rep rate, 10 ns pulses with a 250 μm spot radius). Tests for morphological and electrical damage to the CCD arrays have been reported previously. In new experiments, the micro-damage morphology is examined and correlated with both the observed electrical degradation and newly observed stress effects. We report the observation of surface deformation and lattice defects due to laser-induced stresses in the SiO2 and poly-silicon thin films on the silicon substrate. Measurements of damage for the CID arrays show them to be more resistant to laser damage than MOS structures such as CCD arrays. In addition, electrical degradation of these arrays was observed which affected the video output signal from the devices.