In this paper, we have evaluated the merits of monolithically co-integrated alternate channel CMOS device architecture, utilizing tensile strained germanium (𝜺-Ge) for the pchannel FinFET and variable indium (In) compositional InxGa1-xAs (0.10 ≤ x ≤ 0.53) for the n-channel FinFET. The device simulation models were calibrated using the experimental results of Ge and InGaAs FinFETs, and subsequently transferred to the co-integrated Ge and InxGa1-xAs structure while keeping the device simulation parameters fixed. The device parameters such as VT, ION, IOFF, and SS were determined for identical fin dimensions for n-and p-channel FinFETs as a function of In composition that alters the tensile strain in Ge. These parameters are controllable during the heteroepitaxial growth by varying In composition in InxGa1-xAs. 𝜺-Ge p-FinFET is shown to be superior in terms of SS and ION/IOFF ratio compared to other competing architectures. The co-integrated architecture of CMOS inverter exhibited an optimum performance over a range of In compositions from 20 % to 40 % while driving fan-out FO-1 and FO-4 load configurations.In addition, the CMOS inverter with symmetric rise and fall times as well as noise-immune functionality demonstrated 150 GHz of operating frequency with 30 nW total power dissipation at 20% In composition, and hence a superior power-delay-product comparable to ITRS standards. Moreover, the 3-stage CMOS ring oscillator performance was evaluated with various In compositions to be stable and power efficient. Thus, the co-integrated approach has a potential to (i) simplify large scale CMOS integration, and (ii) be compatible with optoelectronic materials.