A new amorphous silicon reflective sensor optimized for bar-code reading

Abstract We report on a small light-sensing device of novel design based on amorphous silicon (a-Si:H), optimized for bar-code reading applications. The device comprises a 500 μm diameter a-Si:H photodiode having a number of holes within its diameter, allowing light from an LED mounted behind the device to pass through and illuminate the target bar-code.