Ohmic contact formation on GaAs layers with low-temperature molecular-beam epitaxial caps

Molecular-beam epitaxial GaAs layers, grown at 200 or 400 degrees C, show great promise as passivating or insulating films on top of standard n-type MESFET layers (n approximately=1.6*10/sup 17/ cm/sup -3/) grown at normal temperatures (580-600 degrees C). It is shown that ohmic contacts, with specific contact resistances of 10/sup -6/ Omega -cm/sup 2/, can easily be fabricated without removing the cap layers. Preliminary results on capped p-type MESFET layers (p=1.5*10/sup 17/ cm/sup -3/) suggest that a 200 degrees C cap may degrade the contact resistance by a factor of 3-10.<
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