For each SAM (C4, C6, C8, and C10), we measured statistically large numbers of J(V ) curves (sample size N = 383-600 for each n) and constructed Gaussian logarithmic average of J values, 〈log 10 |J|〉 G (where J is in A cm -2 ), versus V curves following previously reported methods. We observed a non-linear increase of 〈log 10 |J|〉 G with V typical for coherent tunneling (Fig. ), but the shape of J(V ) curves for n=4 and 6 are concave but convex for n=8 and 10, which could be caused by over-barrier (or Fowler Nordheim) tunneling. Unfortunately, the currents at low voltage (|V | ≤ 2 V) fall below the experimental noise, resulting in artefacts such as flat regions due to very low currents < 1 pA, preventing us from performing more detailed analysis.