DYNAMIC SHAPE OF THE DEPLETION LAYER OF A SUBMILLIMETER-WAVE SCHOTTKYVARACTOR

Most frequency multipliers at submillimeter wavelengths are based on t he Schottky varactor. The main problem of these multipliers is the out put power, which remains low at frequencies above 500 GHz. The aim of this work is to help the situation by studying the usability of the co nventional equivalent circuit during a fast voltage modulation. The an ode edge effects play an important role in this voltage modulation. Wh ile the fringing fields, due to the edge effects, reduce the capacitan ce modulation in small submillimeter-wave varactors, the edge effects also lessen the effect of electron velocity saturation compared with a n ideal varactor with a pure parallel plate capacitance. The usefulnes s of the static model can be estimated by comparing the three-dimensio nal shape of the depletion layer to the shape given by the dynamic mod el, The dynamic shape can be obtained by solving the potential and ele ctron conduction currents in the epitaxial layer of the Schottky varac tor, In this work the potential and the electron currents have been ca lculated from simplified device physics by using numerical methods.