Removal of Surface Oxide Layer from Silicon Nanocrystals by Hydrogen Fluoride Vapor Etching

We describe the natural oxidation of silicon nanocrystals (SiNCs) and the method of etching the natural oxide layer of SiNC with hydrogen fluoride (HF) vapor. Electrical measurements are conducted in order to investigate the influence of the natural oxidation of SiNCs. The wet HF etching process, which is currently used in the semiconductor industry, results in the removal of all SiNCs from the substrate. Therefore, we use HF vapor etching, which can remove only the natural oxide layer without the removal of SiNCs from the substrate. Consequently, the HF vapor process is suitable for SiNC devices. From electrical measurements, it is observed that current increases by four orders of magnitude after the HF vapor etching treatment. In addition, it is revealed that we can control the thickness of the oxide layer of SiNCs by changing the HF vapor etching time. (C) 2011 The Japan Society of Applied Physics