We report a self-aligned InGaAs Quantum-Well MOSFET (QW-MOSFET) on III-V-O-I substrate fabricated through a tight-pitch process. The ultra-thin body (UTB) III-V-O-I layer structure was fabricated on Si through a direct bonding technique. The III-V MOSFETs, with a self-aligned gate and metal contacts, were fabricated by a gate-last method. For the first time, we demonstrate adjacent devices with contact metal spacing of 150 nm. The fabrication features CMOS compatibility with a wet-etch free, lift-off free and Au-free process in the front end. Transport and short-channel effects (SCE) are studied as a function of back bias. Excellent SCE control is obtained with DIBL and subthreshold swing benchmarked against state-of-the-art III-V-O-I data. The reported technology provides a new path to integrate III-V front-end devices for future high density circuit applications. © 2014 IEEE.