Optimization of novel oxide-free insulated gate structure for InP having an ultrathin silicon interface control layer

Attempts were made to clarify the cause for the poor reproducibility of successful processing accompanied with a low the transconductance in the previous oxide-free InP MISFET having an ultrathin Si interface control layer (Si ICL). A detailed in-situ XPS study made for each step of processing indicated that deficiency of P on the InP surface took place by the irradiation of high energy Si beam during the growth of Si ICL. Then, a modified passivation structure having an In/sub 0.53/Ga/sub 0.47/As cap layer was proposed and investigated. In-situ XPS study indicated that the novel gate structure prevents desorption of P from the InP surface. In-situ contactless C-V method showed a low and wide interface state density distribution with a minimum of 2/spl times/10/sup 11/ cm/sup -2/ eV/sup -1/. A long-gate InP MISFET test device with a gate length of 2 /spl mu/m exhibited a maximum g/sub m/ of 123 mS/mm and a high drain current of 389 mA/mm.