Passivation of Gallium Arsenide Nanowires for Solar Cells

Sammanfattning: A strategic and diverse set of passivation methods for gallium arsenide nanowires wasstudied. Using a time-resolved photoluminescence setup at100 Kand300 K, the radiativerecombination of charge carriers was resolved on a picosecond time scale. Characterizationof these nanowire arrays on their native substrates provided reliable and nondisruptivemeasurements of thousands of nanowires simultaneously.Three promising passivation methods were explored yielding unexpected results. First,an international collaboration was created which identified poly(3-[3,7-dimethyl-octyloxy]thiophene)(P3OOT) as a novel, conjugated polymer-based passivation material. Results were incon-clusive. Second, an established hydrazine-sulfide solution treatment was compared witha low temperature, low vacuum plasma nitridation technique. The hydrazine treatmentunexpectedly demonstrated depassivation whereas the plasma method strongly exceededexpectations. These measurements of plasma treated gallium arsenide nanowires may bethe first publicly documented evidence for passivation using this procedure.Overall, the results of these experiments further demonstrate the strong need for pas-sivation of GaAs nanowires and proposes a new and relatively simple nitrogen plasmamethod which partially achieves this goal.