The Role of Silver Additions in Formation of Sn-Bi-Ag Semiconductor Alloys by Rapid Solidification

Five alloys Sn-5Bi-xAg (x = 0, 1, 2, 3, and 4 in at %) are produced by rapid solidification using melt-spinning technique. From temperature dependence of electrical resistivity (TDR), it is found that the Sn-5Bi-xAg (x = 1, 2, 3, 4 in at %) rapidly solidified by melt spinning technique are narrow band semiconductor alloys. The energy gap Eg decreases by increasing Ag concentration from 203 meV for Sn-5Bi-1Ag to 97.5 meV for Sn-5Bi-4Ag alloy. From x-ray diffraction analysis (XRD), it is found that the Hume-Rothery condition for phase stability is not satisfied for this alloy