Organometallic Epitaxy for GaAs/AlGaAs Microwave Transistors and Integrated Circuits.
Final rept. 15 Jun 80-14 Jun 83,
VARIAN ASSOCIATES INC PALO ALTO CA
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Applications of atmospheric-pressure organometallic-grown GaAs-AlGaAs epitaxial OMVPE structures to potentially improved or new microwave FET structures were investigated. These included AlGaAs buffer layers for low-noise FETs, AlAs buffer layers for power FETs, and use of the selective etching of AlGaAs buffer layers to produce air-isolated FETs. The presence of increased trapping densities in the buffer layers, or surface states on the exposed channel layer in the case of the air-isolated structure, degraded rather than enhanced FET performance. Excellent performance was, however, obtained with conventional GaAs low-noise FETs grown entirely by OMVPE. HEMT structures were also grown by OMVPE, but did not show the increased mobilities of identical structures grown by MBE. GaAsAlGaAs structures analogous to silicon MOSFETs were also fabricated. Inversion of p-type substrates n-channel operation could not be obtained but, unexpectedly, indications were obtained of successful inversion of n-type material p-channel operation.
- Electrical and Electronic Equipment
- Solid State Physics