Hall-effect and sheet-resistivity measurements have been made on silicon samples implanted with Sb, Ga, and As ions at energies between 20 and 75 keV. These measurements determine the weighted average of the number Ns of carriers/cm2 and the carrier mobility in the implanted layer. A combination of Hall measurements and layer-removal techniques was used in some cases to obtain a more accurate value of the number of carriers/cm2 and the depth dependence of the carrier concentration and mobility.For Sb implantations both temperature and dose affect the anneal characteristics. Silicon samples implanted with Sb at room temperature exhibited n-type behavior following anneal at 300 °C, with little increase in Ns up to about 550 °C anneal temperatures. A 600 °C 10-minute anneal produced an order-of-magnitude increase in Ns. This change is associated with reordering of the amorphous layer created during room-temperature implantations. This amorphous layer is not produced in implantations made at temperatures above 450 °C. In low-dose (<1014/cm2) Sb implantations at 500 °C, Ns increased by a factor of 2 to 3 during anneal to 800 °C. In high-dose (>5 × 1014/cm2) Sb implantations, the carrier concentration exceeded the limit set by thermal equilibrium solubility of Sb in silicon. Under these conditions, annealing caused a decrease in Ns toward the value associated with the solubility.Such supersaturation effects were not observed in Ga and As implantations at 500 °C. Annealing to temperatures of 800–900 °C produced a one-to-two order-of-magnitude increase in the number of carriers/cm2. In Ga implantations annealed to 800–900 °C, the number of carriers/cm2 increased approximately linearly with increasing dose and then leveled off at a value near that expected from thermal solubility.The Rutherford-scattering data in the preceding paper indicates that the difference in implantation behavior between various ion species is due to differences in the relative number of ions on substitutional sites.

The anneal behavior of layers implanted with dopants from column III (B, Al, Ga, and Tl) and column V (As, Sb, and Bi) in silicon substrates has been investigated. The ranges of implant conditions were energy 20–50 keV, dose 1013–1015/cm2, and substrate temperature 23°–500°C. Hall-effect and sheet resistivity measurements were used to determine the effective number of carriers/cm2 (Ns)eff and the effective mobility μeff. Analysis of nonuniform distributions of carrier densities and mobilities on these measurements shows that the values of (Ns)eff and μeff can be misleading unless the effect of the depth distributions is allowed for. These distributions have been determined in some cases by the use of layer removal techniques combined with Hall-effect and sheet resistivity measurements. We find in well-annealed implanted samples that the dependence of the mobility on carrier density follows that determined for bulk silicon. In many cases deviation from this relation can be accounted for on the basis of compensation. In the case of aluminum we suggest that this compensation may be accounted for by the presence of interstitial aluminum atoms acting as donors. We have found that interstitial thallium can behave as a donor. The anneal behavior of the implanted layer is influenced by ion species, dose, and substrate temperature. The carrier concentration measured in implantations of column III elements did not exceed the limits of thermal equilibrium solubility as is found for column V elements. In the former case, enhanced diffusion effects are observed. From the known substitutional behavior of column V elements, it is suggested that the anneal behavior in the 600°–800°C range is due to the dissociation of radiation damage complexes.

Optical reflection spectra of crystalline, sputtered, and ion implanted silicon specimens are presented. Characteristic aspects of the spectra of ion implanted specimens are related to lattice damage.

Optical (3–6.5 eV) reflection spectra are presented for crystalline Si implanted at room temperature with 40 keV Sb ions to doses of less than 2×1015/cm2. These spectra, and their deviation from the reflection spectrum of crystalline Si, are discussed in terms of a model based on the average dielectric properties of the implanted region. For samples having a high ion dose (&gt;1015/cm2) the observed spectra resemble the spectra of sputtered Si films. Anneal characteristics of the reflection spectra are found to be dose dependent. These observations are compared to, and found to substantiate, the results of other experimental techniques for studying lattice damage in Si.

The electrical behavior of 20–50-keV Bi implanted layers in silicon has been evaluated using Hall effect and sheet resistivity measurements. Implants of greater than 1014/cm2 performed at room temperature show a large increase in the number of carriers/cm2 for short anneals at ≈600°C that is associated with the reordering of the lattice. Although Rutherford scattering measurements (performed at Chalk River Nuclear Laboratories) indicate that ≈80% of the Bi atoms are substitutional, only ≈20% are effective electrically. The peak value of the carrier density distribution is ten times the corresponding maximum solid solubility.