Importance of the choice of the profile model for a p-n junction in the location of deep levels

The energy levels introduced by Pt in silicon have been measured in a non-abrupt p ⁺-n junction using constant-capacitance thermal-emission rate measurements and a numerical simulation of high frequency-capacitance. Two levels have been detected with activation energies of:E _c -E _T = 0.22 eV with acceptor character and E _T -E _v = 0.34 eV with donor character. The sample preparation and diffusion of Pt is similar to previous works in which an acceptor level E _c -E _T = 0.34 eV was found instead of or besides a donorlike level E _T -E _v = 0.34 eV. Our numerical calculation of the shallow-impurity profile points to the existence of a gradual transition near the metallurgical junction for these samples. We have demonstrated that the well-known model of an abrupt junction is not appropriate for these types of junctions, and could lead to errors in the location attributed to the detected levels. Simulation of the electrical behavior leads to the non-existence of the acceptor level E _c -E _T = 0.34 eV located in the n-side of the junction.