A technique for measuring the overlaps of the gate electrodes of field-effect structures is described. Ion-implanted self-aligned gate FET structures were used to evaluate the lateral spread of low-energy (R P<0.1 μm) high-dosage (5×1015/cm2) phosphorus and boron implantations and was found to be less than 10-5 cm. Sheet resistance of the implanted region can also be evaluated by this technique. Some series resistance effects associated with inadequate annealing as well as two-dimensional field aspects on the threshold voltage associated with short channel devices in this experiment were observed. © 1974 American Institute of Physics.