High-Temperature Pb Doping of SnO2 and Growth Limitations of PbxSn1–xO2 Nanowires Versus Low-Temperature Growth of PbxSn1–xO for Energy Storage and Conversion

Pb doping of SnO2 nanowires grown by the vapor–liquid–solid mechanism on 1 nm Au/Si has been investigated between 500 and 1000 °C via the reaction of Sn-containing Pb with O2 at 10–1 mbar. The SnO2 nanowires have diameters of 50 nm, lengths up to 100 μm, and a tetragonal rutile crystal structure, but they do not contain Pb because of its significant depletion during the temperature ramp and re-evaporation from the surface of the SnO2 nanowires. Consequently, we do not observe a semiconductor to semimetal transition and band gap narrowing. Instead, the Pb reacts with O2, leading to the deposition of PbO directly on Si but not on the SnO2 nanowires, which have carrier densities of ≈1016 cm–3. Furthermore, one-dimensional growth was completely suppressed by increasing the amount of Pb in Sn. As such, Pb doping of SnO2 and the growth of PbxSn1–xO2 nanowires is difficult, if not impossible, because PbO2 nanowires cannot be grown by the vapor–liquid–solid mechanism irrespective of the growth temperature. In con...