Planar isolated GaAs devices produced by molecular beam epitaxy

This paper reports the fabrication of low parasitic capacitance planar beam-leaded structures by means of a novel new technology. The structure is produced by the simultaneous deposition of single crystal and semi-insulating polycrystalline gallium arsenide utilizing the molecular beam epitaxial process. Schottky barrier millimeter wave mixer diodes fabricated with the polycrystalline isolated material have shown normal dc characteristics and substantially reduced parasitic capacitance. Devices measured in a double-balanced downconverter circuit showed a conversion loss of 5.3 dB at 51.5 GHz and 8.5 dB at 103 GHz. This is in excellent agreement with the theoretical conversion loss predicted from the dc characteristics. These devices exceed the performance of structurally identical devices fabricated on conventional n on n⁺material by about 2 dB. Since layers of virtually any desired doping concentration can be produced, the material is potentially applicable to a wide range of devices.