Reducing Screening Effect in Close-Packed Si Field Emitter Arrays

Electric field screening effect in close-packed semiconductor field emitter arrays (FEAs) changes the current distribution among emitter tips, such that those on the edges of the array emit much higher current than those in the middle, leading to poor reliability characteristics. Using analysis, numerical simulations, and experimental verification, three different techniques to suppress electric field screening and achieve uniform current distribution are proposed. These techniques are: 1) utilizing very sharp emitter tips; 2) reducing the anode-cathode distance (ACD) to be in the order of emitter pitch; and 3) using extremely low-doped but long field emitter tips. By adopting these techniques together, a more uniform emission from the array and a high emission current density can be achieved. FEAs with 160 K emitter tips with different ACDs and emitter sharpness were fabricated using electron beam lithography. In an array with sharp emitter tips, reliable emission with a maximum current of 0.7 mA (4.4 nA/tip) and a maximum current density of 1.75 A/cm(2) was achieved.