Electron field emission from amorphous silicon

Hydrogenated amorphous silicon (a-Si:H) is used commercially for large area device fabrication in active matrix flat panel displays as the switching element in the thin film transistors. We have found that a-Si:H thin films and its alloys can be conditioned to field emit electrons at relatively low electric fields. Emission from non-optimised films at macroscopic vacuum fields below 20 V/micron is routinely obtained. The emission field can be lowered to below 10 V/micron by further conditioning. It appears that the Schottky junction between the a-Si:H and Cr substrates or the surface of the layer needs to be modified to get electron emission at reasonably low fields. The a-Si:H needs to be fully depleted so that electrons that enter the films can get 'hot'. It should be noted that by having a three terminal device, with the third terminal placed on the thin film surface better control of the emission maybe achieved. If this were the case, it would then be possible to build a layered a-Si:H film such that the lateral conductivity of the surface layer would allow for the voltage of this layer to be modulated easily.