Porous field emission devices based on polyimide membranes using diode andtriode configurations

Residual gas inside field emission displays (FED) is the most important iss ue related to the device lifetime. Increasing the display area while mainta ining the display thickness unchanged results in lifetime decrease, since t he pressure gradient is fostered. Therefore, improvement of vacuum properti es is a mandatory step towards large area displays. In a prior publication we have demonstrated that porous diamond membranes show good vacuum perform ance, while requiring low emitter switching voltage. In this work, we conti nue the porous membrane development by using polyimide as the base material for the membrane. The use of polyimide instead of diamond allows for easie r production of large area porous FEDs. In addition, we present results of preliminary field emission experiments showing a direct correlation between the emitted current and the number of pores. This result strongly suggests that the emission sites are located at the pore edges in the polyimide mem branes, similar to our observations for diamond membranes. From the theoret ical point of view, we propose a new geometry: still based on the use of po res, but including a grid for triode mode operation. Finally, we present el ectron trajectory simulations that address some of the focusing issues in t he proposed device. (C) 2001 American Vacuum Society.