Improved characteristics of GaAs metal-semiconductor field-effect transistors on Si substrates back-coated with SiO2 by metalorganic chemical vapor deposition

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Abstract
GaAs metal‐semiconductor field‐effect transistors (MESFETs) on Si substrates back‐coated with SiO2 grown at high temperature by metalorganic chemical vapor deposition have shown good pinch‐off and suppressed sidegating. The SiO2 back‐coating suppresses Si incorporation into an undoped GaAs layer during growth, and use of such an undoped layer with a low electron concentration beneath the channel layer improves a pinch‐off characteristic. Higher growth temperature also improves crystallinity of GaAs layers grown on Si and helps to suppress the sidegating effect of GaAs MESFETs. The maximum transconductance of 160 mS/mm and the K value of 46.8 mA/V2 mm have been obtained for a MESFET with 2.5 μm gate length.