Design and fabrication of heterostructure varactor diodes for millimeter and submillimeter wave multiplier applications

摘要

A high frequency diode for use as a frequency multiplier element in the millimeter and submillimeter wavelength region is discussed. The diode, called a high electron mobility varactor (HEMVAR) diode, consists of a Schottky contact along the edge of a two-dimensional electron gas (2-DEG) structure, an ohmic contact to the 2-DEG, and appropriate isolation between the two contact pads. As a negative voltage is applied to the Schottky contact, then depletion layer between the Schottky contact and the 2-DEG expands and the junction capacitance decreases, resulting in a nonlinear capacitance-voltage characteristic. The theory, design and fabrication of the HEMVAR multiplier diode are outlined, and the low frequency results for several prototype devices are presented.