A modified form of deep level transient spectroscopy (DLTS) has been employed to perform energy‐resolved measurements of Si‐SiO2interface states. Decreasing the height of the trap filling pulse from the order of volts, as in the usual DLTS procedure, to tens of millivolts allows trap filling measurements to be made, rendering possible the use of Shockley–Read–Hall theory to show that the degeneracy factor of interface states is around unity. The energy dependence of the capture cross section in the upper band gap is also calculated from Shockley–Read–Hall theory and is contrasted for oxidation ambients with and without added HCl.