Control of the Band-Edge Positions of Crystalline Si(111) by Surface Functionalization with 3,4,5-Trifluorophenylacetylenyl Moieties

• DOI: 10.1021/acs.jpcc.6b03824
• Publication Date: 2016-06-03T14:18:45Z
• Authors: Noah T. Plymale; Anshul A. Ramacha...; Allison Lim; Bruce S. Brunschwig; Nathan S. Lewis
• Keywords: 500; 02 engineering and technology; 540; 0210 nano-technology

Functionalization of semiconductor surfaces with organic moieties can change the charge distribution, surface dipole, and electric field at the interface. The modified electric field will shift the semiconductor band-edge positions relative to those of a contacting phase. Achieving chemical control over the energetics at semiconductor surfaces promises to provide a means of tuning the band-edge energetics to form optimized junctions with a desired material. Si(111) surfaces functionalized with 3,4,5-trifluorophenylacetylenyl (TFPA) groups were characterized by transmission infrared spectroscopy, X-ray photoelectron spectroscopy, and surface recombination velocity measurements. Mixed methyl/TFPA-terminated (MMTFPA) n- and p-type Si(111) surfaces were synthesized and characterized by electrochemical methods. Current density versus voltage and Mott–Schottky measurements of Si(111)–MMTFPA electrodes in contact with Hg indicated that the barrier height, Φb, was a function of the fractional monolayer coverage o...