We present a simulation modeling chain for nano-scaled III/V quantum-well MISFETs. Our methods are based on physical rather than empirical modeling, which allows to obtain predictive simulation results with very few fitting parameters. We use a recent InGaAs-based technology from Intel [1] to validate our simulation results which show excellent agreement with measured capacitance and conductance curves. We further evaluate the properties of a 60 nm long InGaAs quantum-well transistor, finding a sub-threshold slope of 73.5 mV/dec and a DIBL of 103.8 mV/V. A fast numerical computational framework ensures high modeling flexibility; at the same time execution times are kept short making our approach an ideal replacement for empirical device modeling which is still pervasive in TCAD.