BEAM FOCUSING CHARACTERISTICS OF SILICON MICROTIPS WITH AN INPLANE LENS

Single microtips, 2 x 2 and 10 x 10 arrays of microtips surrounded by an integrated focusing ring, were fabricated and their focusing charac teristics experimentally investigated. Observation of the beam on a ph osphor screen shows that the focusing is very effective for single mic rotips and 2 x 2 arrays; moreover, the reduction in emitted current is much smaller than for double-gate focusing, 10 x 10 arrays of microti ps, however, do not generate very focused beams. These results agree w ell with simulations, The possibility of simultaneous focusing and def lecting is also discussed, and a new structure combining the advantage s of double-gate and surrounding ring focusing is suggested.