Photoluminescence induced from hot Ge implantation into SiO2

Abstract

Up to the present, by using the ion implantation technique, photoluminescence (PL) from Ge nanocrystals (Ge NCs) was obtained by room temperature (RT) Ge implantation into a SiO2 matrix followed by a high temperature anneal. In this way two PL bands were observed, one at 310nm and the second, with much higher yield at 390nm. In the present work we have used another experimental approach. We have performed the Si implantation at high temperature (Ti) and then, we have done a higher temperature anneal (Ta) in order to nucleate the Ge NCs. With this aim we have changed Ti between RT and 600°C. By performing the implantation at Ti=350°C we found a PL yield four times higher than the one obtained from the usual RT implantation at the same fluence. Moreover, by changing the implantation fluence between Φ=0.25×1016 and 2.2×1016Ge/cm2 we observed that Φ=0.5×1016Ge/cm2 induces a PL yield three times higher as compared to the usual RT implantation fluence. In conclusion, using a hot Ge implantation plus an optimal Ge atomic concentration, we were able to gain more than one order of magnitude in the 390nm PL yield as compared with previous ion implantation results.