Dangling-to-Interstitial Oxygen Transition and Its Modifications of the Electronic Structure in Few-Layer Phosphorene

In
this work, oxidation processes are correlated with the current–voltage
characteristics of few-layer black phosphorus obtained by liquid-phase
exfoliation. Black phosphorous (BP), a room-temperature p-type semiconductor,
exhibits an anomalous switching behavior between 373 and 448 K. The
anomalous increase in electrical resistance is explained using a combined
spectroscopic and DFT approach. The activation energy for thermally
activated electrical conductance was calculated from the current–voltage
characteristics and correlated with the oxidation processes. The activation
energy for thermally activated electrical conductance in the dangling
oxide BP phase was found to be 79.7 meV, ∼ 40 times lower than
that in the interstitial counterpart. First-principles calculations
reveal electronic differences between dangling and interstitial oxides,
and electrical resistance measurements reveal a Schottky-to-ohmic
contact formation related to the differences in the calculated work
function of dangling and interstitial oxides. We propose that this
phenomenon can be exploited as a fast, economical method for the evaluation
of the oxidation processes in few-layer BP.