This article describes a process flow which has enabled the first demonstration of functional, fully self-aligned, 40 nm gate length replacement gate enhancement mode GaAs metal-oxide-semiconductor field-effect transistors (MOSFETs) with Ga(x)Gd(y)O(z) as high-kappa dielectric, Pt/Au metal gate stack, and SiN sidewall spacers. The flow uses blanket metal and dielectric deposition and low damage dry etch modules. As a consequence, no critical dimension lift-off processes are required. As a gate replacement approach has been developed, the process is suitable for easily incorporating different gate metals, opening the way to work function engineering to control threshold voltage and so is a significant step forward to the demonstration of high performance "siliconlike" III-V MOSFETs. (C) 2010 American Vacuum Society. [DOI: 10.1116/1.3501355]