Improvement in the quantum efficiency of silicon photodetectors at near IR wavelengths by edge illumination

The concept of illuminating a silicon photodetector along an edge to increase the light propagation path through the depletion region and thus to increase quantum efficiency at near IR wavelengths is introduced. Quantum efficiency measurements using both a GaAlAs laser and a He-Ne laser are included. These measurements show an improvement in quantum efficiency at 0.83 micron for edge illumination over normal incidence of 75 percent for a photodiode and of 142 percent for a MOS capacitor photosensor.