Design Considerations and Quantum Confinement Effect in Monolithic ε-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
$\varepsilon $
-Ge /InxGa
$_{{1}-{x}}$
As hybrid CMOS system. In this system, the In compositional InxGa
$_{{1}-{x}}$
As and tensile-strained Ge (
$\varepsilon $
-Ge) grown on the InxGa
$_{{1}-{x}}$
As layer were used as n- and p-channel FinFETs, respectively. The In composition in InxGa
$_{{1}-{x}}$
As layer (lattice matched with graded InxAl
$_{{1}-{x}}$
As buffer) determines the amount of tensile strain in Ge. This hybrid system utilizes the benefits of metamorphic (InxGa
$_{{1}-{x}}$
As/InxAl
$_{{1}-{x}}$
As) as well as pseudomorphic (
$\varepsilon $
-Ge/InxGa
$_{{1}-{x}}$
As) heteroepitaxy to create high-performance tunable complementary devices, suitable for 0.5 V CMOS operation. The device metrics such as, threshold voltage, ON-current (
${I}_{\text {on}}$
), OFF-current (
${I}_{\text {off}}$
), subthreshold-swing (SS), and drain-induced barrier lowering (DIBL), and their dependence on material and geometrical parameters were evaluated using self-consistent 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/
$\mu \text{m}$
, 27 nA/
$\mu \text{m}$
, 85, and 95 mV/dec, respectively. With the effect of QC, we identify a transition fin width (
${W}_{T}$
) associated with scaling of alternate channel FinFETs, at which the performance is optimum and below
${W}_{T}$
, 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.