A method for determining an active dopant concentration profile of a semiconductor substrate based on optical measurements is disclosed. The active dopant concentration profile includes a concentration level and a junction depth. In one aspect, the method includes obtaining a photomodulated optical reflectance (PMOR) amplitude offset curve and a PMOR phase offset curve for the semiconductor substrate based on PMOR measurements, determining a decay length parameter based on a first derivative of the amplitude offset curve, determining a wavelength parameter based on a first derivative of the phase offset curve, and determining, from the decay length parameter and the wavelength parameter, the concentration level and the junction depth of the active dopant concentration profile.