Influence of Point Defects on GaAs Devices

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From electron-irradiation studies, it is known that point defects can strongly affect the electrical properties of GaAs-based MESFET's, MODFET's, solar cells, resonant-tunneling diodes, MIMIC circuits and other devices. As an example, 1 × 1016 cm−2, 1 MeV electrons reduce the transconductance in a 1 μm by 200 μm MESFET by nearly an order of magnitude. Fortunately, annealing at 350 °C for 10 min. can largely restore the device performance, although not without some adverse effects. Point defects, or simple point defect complexes, can also exist in as-grown GaAs and affect devices in several different ways. For example, an As-rich stoichiometry can lead to an abundance of Ga vacancies, and thus to a higher Si donor activation in implanted MESFET devices; however, it can also promote an increase in unwanted impurities which sit on the Ga site. As another example, extremely high (> 3 × 1019 cm−3 ) concentrations of As antisites, which are found in MBE GaAs grown at 200°C, lead to very unusual electrical and optical properties, and make possible a highly useful buffer material and a very fast photoconductive switch. However, there are also adverse effects here, such as slow-transients in some MODFET devices, which may result from defect diffusion. Thus, the effects of point defects in GaAs devices must be understood.


Presented at the 1990 MRS Spring Meeting, San Francisco, CA.

Copyright © Materials Research Society 1990.



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