| In this work the characteristics of diodes and bipolar junction transistors (BJTs) were used to detect defects in silicon wafers. Characteristics such as forward bias turn on voltage, reverse bias breakdown voltage, and forward bias resistance were investigated. The size of the devices was of the order 100 mum. The silicon defects in the wafer under test were vacancies (e.g. the density of ∼1000 nm vacancy clusters was 105--10 6 cm-3), which were enriched in the center of the wafer, and interstitials (e.g. the density of interstitial clusters was ∼10 4cm-3) distributed on the outer rim of the wafer.; Eight inch research wafers with a high radial vacancy-to-interstitial gradient were obtained from MEMC Electronic Materials Inc. Device arrays were put onto this silicon in collaboration with the Electrical Engineering Department at the University of Illinois, Urbana-Champaign. Variations between devices, in the I-V curve of pn-junctions of diodes and BJTs, were observed. A possible explanation for this shift is the radial defect gradient in the silicon. |
