Compatibility issues of Si technology with higher band gap materials for RF applications

Now-a-days microwave (MW) electronics is an extremely rapid developing field in semiconductor electronics. For the present and near future demand, research is progressing for the development of high speed and high power density RF devices fabrication beside main stream Si based research. For mixed and RF signal performance, Si still has limitations for it further scaling due to excess leakage of current and low trans-conductance or fT and f Max. So, suitable alternative materials device fabrication is potential. In this paper doping profile of GaAs channel and compositional (% of Al) variation in AlGaAs layer for schottky contact for AlGaAs/GaAs compound semiconductor (CS) based HEMT (high electron mobility transistor) is evaluated. Besides that, gate oxide thickness effects on covalent bonded Si based nMOS gate turn on time and ON/OFF current have also been evaluated. It appears that increasing Al composition in AlGaAs and more doping in GaAs layer enhances channel trans-conductance while low % of Al in AlGaAs layer and low doping in GaAs layer increases ON/OFF current ratio (reduces leakage current). In case of Si MOS, decreasing oxide layer thickness, transconductance is increased but ON/OFF current ratio is decreased (increase leakage current).