The room-temperature photoluminescence of Si nanocrystals in a-Si matrix composite system produced by the irradiation of silicon with ions of high and medium masses

Previously, it was established by us that at an irradiation of monocrystalline silicon with heavy ions, the system possessing room-temperature photoluminescence (PL) is formed. Thereby, in general, two PL peaks are observed: at 700–750 and 900–1000 nm. First peak was assigned to Si nanoinclusions which remains inward the Si matrix at ion-beam amorphization. Other peak is associated with amorphous phase. In the given work, these investigations are continued for more reliable determination of PL mechanisms. Silicon is irradiated with Ge, As (80 keV) and Ar, Ne (150 keV) ions. After that some samples are subjected to annealing at about 300 °C (0.5 h). For all annealed samples, it is established that the peak at 700–750 nm noticeably expressed only for doses close to the amorphization one. Whereas the second peak arises at amorphization dose and it remains at higher doses. This confirms the model, according to which the first peak is caused by the remnant nanocrystals and the second one is associated with a-Si. Possibly, the PL of a-Si is enhanced by the presence of Si nanocrystals, but other factors also affect the PL intensity (the degree of radiation damage, irrelevant impurity penetration, etc.). Such an interpretation is confirmed by electron spin resonance (ESR) data, which demonstrates the extreme behavior in transient to amorphization dose region.