Optimisation of fully depleted SiGe channel with raised source/drain buried oxide nMOSFET

Abstract

A fully depleted silicon-germanium (SiGe) n-channel heterojunction MOSFET with raised buried oxide in the source/drain is reported under the consideration that channel is made of SiGe and source/drain regions is made of silicon (Si). Due to the raised buried oxide source/drain region, it provides better current due to the improvement of mobility in the channel region and also reduce the surface scattering effects. Bandgap engineering has been done to improve the electrical behaviour of the device. Simulation work for different parameters on the device has been carried out and presented in the paper. The electrical characteristics of the proposed device are optimised by varying the device dimensions. Effect of mole fraction on threshold voltage (VTH), Subthreshold swing (SS), ION and IOFF current ratio is analysed. It is observed that due to presence of SiGe channel and the raised source/drain, the proposed device shows enhancement in electrical characteristics. A CMOS inverter through proposed device has been implemented and the effect of mole fraction on its characteristic is reported. Average delay increases as mole fraction increases.