| Abstract
| - FTIR studies of HF-etched silicon nanowires (SiNWs) revealed that the surfaces are hydrogen-terminated with three types of hydrides: SiH, SiH2, and SiH3. The H-terminated SiNW surfaces showed good thermal stability, with hydrogen desorption from SiH3, SiH2, and SiH moieties occurring at ∼550, ∼650, and ∼750 K, respectively. At ∼850 K, the surfaces are free of silicon hydrides. The H-passivated surfaces of SiNWs showed good stability in air under ambient conditions but relatively poor stability in water.
- Attenuated total reflection Fourier transform infrared (FTIR) spectroscopy was used to characterize the surfacespecies on oxide-free silicon nanowires (SiNWs) after etching with aqueous HF solution. The HF-etched SiNWsurfaces were found to be hydrogen-terminated; in particular, three types of silicon hydride species, the monohydride(SiH), the dihydride (SiH2), and the trihydride (SiH3), had been observed. The thermal stability of the hydrogen-passivated surfaces of SiNWs was investigated by measuring the FTIR spectra after annealing at different elevatedtemperatures. It was found that hydrogen desorption of the trihydrides occurred at ∼550 K, and that of the dihydridesoccurred at ∼650 K. At or above 750 K, all silicon hydride species began to desorb from the surfaces of theSiNWs. At around 850 K, the SiNW surfaces were free of silicon hydride species. The stabilities and reactivitiesof HF-etched SiNWs in air and water were also studied. The hydrogen-passivated surfaces of SiNWs showedgood stability in air (under ambient conditions) but relatively poor stability in water. The stabilities and reactivitiesof the SiNWs are also compared with those of silicon wafers.
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