A parasitic resistance measurement method exploiting gate current–density characteristics in ultra-short Schottky-gate FETs

Gate forward current–density characteristics of ultra-short Schottky-gates are studied with experiments and calculation to clarify the mechanism of inhomogeneity in the current density along the gate length. Then, by exploiting the gate current–density characteristics, a new DC measurement method is proposed to evaluate the parasitic source and drain resistances, Rs and Rd, in the Schottky-gate FETs. The method is based on a gate-probing end-resistance technique, which can evaluate the values Rs and Rd simply and accurately by using DC measurement, even if the device has an ultra-short gate length Lg of less than 0.15 μm, because it applies a bias larger than a built-in voltage Vbi of the Schottky junction to the gate electrode in order to eliminate inhomogeneities in the gate current–density characteristics.