Inelastic electron tunneling spectroscopy (IETS) [R. C. Jaklevic and J. Lambe, Phys. Rev. Lett. 17, 1139 (1966); R. G. Keil et al., Appl. Spectrosc. 30, 1 (1976); K. W. Hipps and U. Mazur, J. Phys. Chem. 97, 7803 (1993); U. Mazur et al., Anal. Chem. 64, 1845 (1992); P. K. Hansma, Tunneling Spectroscopy (Plenum, New York, 1982)] measurements are performed on Si nanowire (NW)/SiO2/Al NW tunnel junctions. The tunnel junction area is 50 120 nm and tunneling occurs across a 10 nm thick SiO2 layer. IETS measurements are performed at 300 K for ammonium hydroxide (NH4OH), acetic acid (CH3COOH), and propionic acid (C3H6O2) molecules. The I–V, dI/dV–V, and d2 I/dV2 –V characteristics of the tunnel junction are measured before and after the adsorption of molecules on the junction using vapor treatment or immersion. Peaks can be observed in the d2 I/dV2 –V characteristics in all the cases following molecules adsorption. These peaks may be attributed to vibrational modes of N–H and C–H bonds
