We present an inverse modeling technique to determine the two-dimensional (2D) dopant profile of a metal-oxide-semiconductor field-effect transistor from electrical measurements. In our method, the profile is formulated using two tensor product splines (TPSs). This analytical representation is general, compact, and flexible. It simplifies the profile determination problem to the extraction of the TPS coefficients from experimental data. We show the results of applying the new technique on data collected from a sub-0.5 mu m complementary metal-oxide-semiconductor technology with various source/drain implants. We also compare the measured and simulated I-V and C-V characteristics. The results illustrate the importance of accurate 2D dopant profiles for short-channel device simulation and modeling.