Papers by Author: Markus Zschorsch

Abstract: To determine the electrically inactive fraction of As or P in heavily doped as-grown Czochralski Si 4-point resistivity and SIMS measurements were carried out. No clear trend for the electrical inactive fraction was found with an increasing dopant concentration, though a mean electrical inactive fraction of 11.5% for As doping could be determined.Experimental results on a dopant-vacancy complex in as-grown Si are scarce, hence temperature-dependent positron annihilation lifetime spectroscopy (PALS) was carried out on several heavily As and P doped as-grown Si samples. The measured average positron annihilation lifetime τ_av is between 218 ps and 220 ps. No temperature dependent effect on τ_av could be observed. Therefore, it can be concluded that in the studied doping range the dopant-vacancy complexes do not exist. The reason for the inactivation of the dopant has to be found elsewhere. A possible explanation can be the formation of dopant precipitates.

Abstract: The content of interstitially solved oxygen (Oi) in heavily boron doped silicon (9- 29 m
cm) were measured by low temperature Fourier transform infrared (FTIR) spectroscopy. Therefor an alternative thinning technique for silicon is used: by alkaline potassium hydroxide etching (KOH) prepolished silicon specimens are thinned down to 8 - 60 microns. The optimal end thickness depends on the boron concentration which specifies the free carrier concentration. Specimens with three different boron concentrations (9/19/29 m
cm) were examined. The results are compared with gas fusion analysis (GFA) measurements. Furthermore the precipitated oxygen Oi was measured for a RTA process (20s@1250°C) with subsequent growth steps (4h@780°C + 16h@1000°C).