Novel GaAs Schottky barrier diode structures

Design of Schottky barrier diodes for use in high frequency applications is limited by the tradeoff between V₀, the inverse slope parameter, and the R_sC _j0 product. This, in turn limits the minimum noise and conversion loss of the receivers which use these devices. Two technologies, the graded doped barrier diode and the Schottky barrier membrane diode, which enhance the performance of the device by reducing parasitic elements, are discussed. The graded doped barrier diode (GDB) has reduced the minimum possible R_sC_j0 for a given V₀. For a receiver using a standard device, the GDB will provide an improvement in noise without sacrificing conversion loss. The Schottky barrier membrane diode greatly reduces the skin effect resistance. Compared to a standard device, this structure will yield a significant improvement in conversion loss. GaAs membranes of 2.7-μm thickness have been fabricated and the current research emphasis is on the formation of the ohmic contact. Very recent work on ohmic contracts has provided many possible solutions, and these contact technologies are being evaluated for use in this device. Successful fabrication of a Schottky barrier membrane diode will greatly improve the sensitivity of submillimeter-wavelength heterodyne receivers