Germanium Nanowire Synthesis via Localized Heating and a Comparison to Bulk Processes

In this work, we compare the localized synthesis of germanium nanowires (GeNWs) to germanium nanowires synthesized under a globally high temperature environment. The localized synthesis of germanium nanowires is presented for the first time using the resistive heating of MEMS microbridges. The results of the localized synthesis process are then compared with the results of well-established high temperature synthesis processes for germanium nanowires. The effect of heat source and local temperature gradients on the resulting nanowires is assessed. The results suggest that optimal nanowire synthesis conditions in a high temperature furnace environment are no longer optimal in localized heating based synthesis. More specifically, there is a significant reduction in growth rates with the localized process. Differences in nanowire quality are observed as kinking and bending of the nanowires are a common result of the localized process yet rare in germanium nanowires synthesized in a global heating environment. Nanowires grown in a global heating environment exhibit larger average wire diameters, approximately 80 nm larger, compared to those synthesized using the localized heating process. Finally, nanowire tapering which is evident in the global heating process is not prevalent in the localized process.