Photoemission studies of passivation of germanium nanowires

• Published in: Applied physics letters 2005-12, Vol.87 (26), p.263109-263109-3
• Main Authors: Adhikari, Hemant, McIntyre, Paul C., Sun, Shiyu, Pianetta, Piero, Chidsey, Christopher E. D.
• Format: Article
• Language: English
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.2158027

The surface of single crystal germanium nanowires grown by cold-wall chemical vapor deposition was studied by synchrotron radiation photoemission spectroscopy and also by conventional x-ray photoelectron spectroscopy. The surfaces of the nanowires are not oxidized from which we infer that they are hydrogen passivated as-grown. Exposure to laboratory atmosphere leads to germanium oxide growth with oxidation states of Ge 1 + , Ge 2 + , Ge 3 + , while exposure to UV light leads to a predominance of the Ge 4 + oxidation state. Most of the surface oxide could be removed readily by aqueous HF treatment which presumably leaves the nanowire surface hydrogen terminated. The HF-treated surface has more limited stability in air. Alternatively, chlorine termination could be achieved by aqueous HCl treatment of the oxide-coated nanowires. This chlorine termination was found to be more stable in air than the putative hydrogen termination achieved by aqueous HF treatment.