Molecular beam epitaxy regrowth and device performance of GaAs-based pseudomorphic high electron mobility transistors using a thin indium passivation layer

Using the technique of molecular beam epitaxy, an indium passivation layer as thin as several tens of angstroms was implemented to protect underlying III-V epilayers from carbon and oxygen contamination. After the subsequent desorption of the passivation layer, GaAs-based pseudomorphic high electron mobility transistors (PHEMTs) were regrown. Negligible residual carriers were detected at the interface between the regrown PHEMTs and the underlying layer, resulting in a superior performance. The regrown PHEMTs with a 1×100 μm² gate demonstrated an extrinsic transconductance g_me as high as 330 mS mm^-1. Microwave measurements showed that the current gain cut-off frequency f_t was 26.5 GHz and the maximum oscillation frequency f_max was up to 48 GHz. A small-signal equivalent circuit model of the regrown PHEMTs was also evaluated.