Optical, electrical, and diffusion properties of hafnium in silicon

Optical properties, deep levels, and diffusivity of Hf in Si have been studied. A new photoluminescence (PL) band in the infrared energy range associated with hafnium implanted in silicon has been found. A shift in the position of photoluminescence peaks observed on the samples implanted with two different isotopes of Hf confirms the Hf-related origin of the observed photoluminescence band. Activation of the Hf-optical centers requires a critical 1000°C anneal step. The PL spectra depends on the cooling rate of the sample. The spectrum consists of five peaks in the rapidly quenched sample as opposed to twenty-one in the slowly cooled sample. The luminescence characteristics of three PL lines with relatively high intensity were investigated as a function of excitation power, temperature, and hydrostatic pressure. The 943.8 meV line was found to be associated with an exciton complex, while the 896.6 meV line originates from impurity bound exciton. The 896.6 meV emission line appears to be related to a Hf-related deep level defect at EC-0.22 eV, the 845 meV line to a deep level defect at EC-0.27 eV however; hydrostatic pressure measurements indicate that the 845 meV peak could be an internal transition. It is also found that oxygen co-implantation enhances the PL intensity in rapidly quenched samples.;Several deep level defects were found for Hf in both the upper and lower half of the silicon band gap, and their parameters were tabulated. Energy levels, concentrations, and capture cross sections were determined for all Hf defects. The DLTS spectra depends on the cooling rate. For defects that appeared in the highest concentration, trap filling experiments were conducted to determine their capture cross sections directly. Electric field enhanced emission due to the Poole-Frenkel effect was experimentally confirmed for defect N146 found in the upper half of the bandgap. C-V, DLTS and TSCAP results confirm the donor nature of this dominant defect in the deep level spectra. In the lower half of the bandgap, defect P143 was found to have a temperature dependent capture cross section whose capture barrier was found to be 0.04 eV.;Diffusivity of Hf was studied using two methods for Hf incorporation in Si-ion implantation and sputtering. Ion implanted samples were annealed at various temperatures. Since no broadening of the Hf profile was observed, interpretation of depth profiles could not be used to determine the Hf diffusivity using the conventional approach. (Abstract shortened by UMI.).