High voltage gain MESFET amplifier using self-aligned MOCVD grown planar GaAs nanowires

We have recently demonstrated the growth of self-aligned unidirectional GaAs planar nanowires (NWs) on GaAs (110) substrate by MOCVD through Au-catalyzed vapor-liquid-solid (VLS) mechanism ^[1]. These planar NWs, in contrast with the vertically aligned ones, are compatible with traditional planar processing and thus very promising for realizing NW based circuits in a deterministic manner. GaAs MESFETs have been widely used as components of amplifiers in microwave applications. However, MESFETs often show low output resistance, thus low voltage gain for the amplifiers resulting from the large channel length modulation effect ^[2]. This is because the thick depletion layer that exists between gate and the actual conducting channel degrades the gate control, which is similar to the case in MOSFETs. It is anticipated that a nanowire (NW) channel with multi-gate structure can improve the gate electrostatics and reduce the channel length modulation effect as a result. Here we present a gate length scaling study of planar NW MESFETs and demonstrate a simple amplifier using them.