Photoluminescence band of Hf origin in hafnium-implanted silicon in the energy range 700 meV to 950 meV

A new photoluminescence (PL) band in the energy range of 700 to 950 meV associated with hafnium implanted in silicon is reported. 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 1000°C anneal step. The intensity of the PL lines depends on the cooling conditions. The spectrum consists of 5 peaks in the rapidly quenched sample as opposed to 21 in the slowly cooled sample. Temperature- and excitation power-dependent PL measurements were performed to identify their nature. The 943.8 meV line was 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. The pressure measurements indicate that the 845 meV peak could be an internal transition. It is also found that oxygen coimplantation enhances the PL intensity in rapidly quenched samples.