Molecular Beam Epitaxial Materials Study for Microwave and Millimeter Wave Devices.
Final rept. 24 Sep 76-23 Oct 78,
GEORGIA INST OF TECH ATLANTA ENGINEERING EXPERIMENT STATION
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This report describes the study of molecular beam epitaxial materials for microwave and millimeter wave applications. Analytical techniques including electron diffraction, residual gas analyzer, Auger spectroscopy, electron microprobe, deep level trap spectroscopy, photoluminescence, Schottky barrier diodes, Hall measurements, and X-ray topography were used to relate the deposition conditions to the structural and electrical properties of unintentionally doped layers of GaAs grown by MBE. During the investigation, individual system components were identified which were incompatible with achieving low residual doping levels. Modifications in the system yielded epi-layers with reproducible background doping levels of the order of 10 to the 14th power to 10 to the 15th powercu cm. Two n-type dopants Sn and Ge and one p-type dopant Be were investigated and used to grow layers for device evaluation. Millimeter wave mixer diodes fabricated from MBE GaAs showed high performance. Layers were also grown for Schottky barrier FETs, Schottky barrier and p-n high-low IMPATTs, and p-n hyperabrupt varactors, and the static characteristics of these devices were investigated. Barrier heights for Au, Al, and Ag Schottky diodes, on freshly grown layers were lower than barrier heights measured for diodes formed on oxidized GaAs layers. Epilayers of GaAs were also grown on 111 Ge substrates and surface characterizations made for evaluation of crystalline perfection.
- Atomic and Molecular Physics and Spectroscopy