Characterization of ultrashallow dopant profiles using spreading resistance profiling

Abstract

It has been noticed that for ultrashallow ion implanted dopant profiles, the metallurgical junction is not at the same location as the peak of the spreading resistance profile, i.e., the on-bevel junction. This can be attributed to the carrier redistribution effect. Furthermore, the pressure under the spreading resistance probes causes band-gap narrowing of the material under the probes. This pressure-induced band-gap narrowing effect increases the intrinsic carrier concentration of the semiconductor material. An inverse algorithm used to convert spreading resistance profiles into the electrically active dopant profiles, taking both carrier redistribution and band-gap narrowing into account, is presented in this article. Using this algorithm, the depth of the metallurgical junction of a shallow ion implanted p ϩ n profile is determined to be 0.121 m from the surface, whereas the on-bevel junction depth is 0.089 m. The recovered dopant concentration profile agrees very well with that obtained from secondary ion mass sepctrometry. The algorithm is shown to work very well also for an n ϩ p junction.

Appearance of effective surface conductivity: An experimental and analytic study

“…It is the behavior of ψ(k; 0) for large k that is important here. There are two asymptotic relations for large r depending on whether condition (10) or (11) is considered. For (10) we can assume, that ψ(0; 0) = 0, and then…”

“…For the potential-free case the eigenfunctions for the eigenvalues k 2 values yield cos(kz) if condition (10) is to be satisfied and cos (kz + ϕ(k)) if condition (11) holds. The phase shift ϕ is given by the formula…”

“…This is why it appears to be a hint as to how the conductivity should be modeled close to surfaces. Noteworthy, numerical algorithms often deal with thin slices of constant conductivity [10,20] parallel to the surface. As such, they assume condition (5).…”

“…Conductance measurements on beveled surfaces have been used successfully to reconstruct the doping profile below the surface with a spreading resistance analysis [8][9][10]. These methods, however, rely on refined numerical algorithms and offer no analytic insight.…”

Hybrid Organic-Inorganic Solar Cells

“…These observations indicate that the parasitic shunt may be associated with pressure induced bandgap narrowing, well documented in cases of four-point probe and spreading resistance measurements. [138][139][140][141] The simulations, results of which are shown in Figure 6.9, indicate that the current-voltage characteristic of the PEDOT-based diode below a bias of 1 V can be accounted for entirely with only the hole current component. At higher biases, the electron current starts to contribute to the IV characteristic.…”