Unique electronic band structures of hydrogen-terminated {112} silicon nanowires

Band structure mutation from an indirect to a direct gap is a well-known character of small hydrogen-terminated {110} and {111} silicon nanowires (SiNWs), and suggests the possible emission of silicon. In contrast, we show that hydrogen-terminated {112} SiNWs consistently present indirect band gaps even at an extremely small size, according to our calculations using density functional theory. Interestingly, the band gap {112} of SiNWs shows a quasi-direct feature as the wire size increases, suggesting the possibility of using medium SiNWs in optoelectronic devices. This result also indicates that the electronic structures of SiNWs are strongly orientation dependent. © IOP Publishing Ltd.