Beam characteristics of a high-gain avalanche rushing amorphous photoconductor field-emitter image sensor

A new type of image sensor that uses a field emitter array FEA.and a high-gain avalanche rushing amorphous photoconductor HARP.target, with a mesh electrode inserted between them, has been designed and tested. The effects of the voltage and position of the electrode were investigated in a vacuum chamber. The resolution and dynamic range were improved by applying an adequate mesh voltage. The voltage needed for the mesh electrode was decreased by reducing the distance between the FEA and the electrode. Most of the electrons emitted from the FEA are captured by the mesh electrode and therefore contribute nothing to the read-out of the signal on the target. The mesh electrode structure thus needs further study. In addition, the decelerating electric field formed between the mesh and target needs to be considered because it spreads the electron beam, thus degrading the resolution and dynamic range of the device. q1999 Elsevier Science B.V. All rights reserved.