Controlled semiconductor capacitors

This paper discusses the development of a new class of semiconductor devices-"controlled semiconductor capacitors" (CC\´s) in which the capacitance can be varied using an external control of radiation (e.g., light) or current. The high-speed control of a capacitance by an external source has had no satisfactory solution to date. We have developed the theory and simulation and design methods, and have obtained experimental results which allow us to address this problem. In principle the problem of capacitance control can be solved using electrical schemes of various combinations of traditional discrete element such as capacitors plus semiconductor diodes, or only diodes. However, with silicon devices such schemes are impractical and uneconomical. We show that controlled capacitors can be designed practically and effectively using two GaAs PIN diodes with a near-fully compensated i-region of controllable width, or a PIN diode and a high voltage GaAs Schottky diode.