Design Considerations and Quantum Confinement Effect in Monolithic -Ge/InxGa1-xAs Nanoscale FinFETs Down to N5 Node

In this work, we have studied the effect of material parameters (indium (In) composition and doping), geometrical parameters [channel length L, fin width W, aspect ratio (AR)], and quantum confinement (QC) on the performance and operability of a epsilon-Ge/InxGa1- xAs hybrid CMOS system. In this system, the In compositional InxGa1- xAs and tensile-strained Ge ( epsilon-Ge) grown on the InxGa1- xAs layer were used as n- and p-channel FinFETs, respectively. The In composition in InxGa(1-x)As layer (lattice matched with graded InxAl1- xAs buffer) determines the amount of tensile strain in Ge. This hybrid system utilizes the benefits of metamorphic (InxGa(1-x)As/ InxAl1-xAs) as well as pseudomorphic (epsilon-Ge/InxGa(1-x)As) heteroepitaxy to create high-performance tunable complementary devices, suitable for 0.5V CMOS operation. The device metrics such as, threshold voltage, ON-current (Ion), OFF-current (Ioff), subthreshold-swing (SS), and drain-induced barrier lowering (DIBL), and their dependence on material and geometrical parameters were evaluated using selfconsistent analytical solvers scaled down to the N5 node. At these scaled dimensions, this hybrid system demonstrated ultralow leakage current and SS for the n-FinFET and p-FinFET of 10 pA/mu m, 27 nA/ mu m, 85, and 95 mV/dec, respectively. With the effect of QC, we identify a transition fin width (WT) associated with scaling of alternate channel FinFETs, at which the performance is optimum and below WT, the benefits of scaling are diminished. Moreover, this hybrid system has a potential to find applications in optoelectronic and RF systems as well as high-performance computing.