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

Abstract

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.

Electronic work function modulation of phosphorene by thermal oxidation

“…Figures 4 and 5 show how the oxidation of phosphorene induces fluctuations of the work function that affect the performance of transducers and other applications based on phosphorene. The computational results for surface phosphorene oxides (dangling and interstitial oxides) show that the increasing concentration of oxygen in dangling position results in a higher work function while the conversion of dangling to interstitial oxides is characterized by a decay of the work function [26]. Fluctuations of the work function of phosphorene have been reported empirically at the early stages of oxidation [42].…”

“…Previously, the oxidation of phosphorene has been related to the detection of endothermic processes, variations in the Raman spectrum [27], and Schottky-to-ohmic transitions in the current-voltage characteristics [26]. Particularly, In-situ Raman measurements indicate a large deformation in the c direction of the lattice by a larger than expected redshift of the A 1 g mode at high temperatures.…”

“…This can be used as a proxy indicator of the presence of interstitial oxygen using vibrational spectroscopy, but clear electronic evidence was missing or sometimes contradictory. Later on, computational studies show that interstitial oxygen unlike dangling is characterized by a smaller work function and the difference between both species can be as large as 1 eV, thus it was easily traced using current-voltage characteristics [26]. Nevertheless, the previous measurements of currentvoltage characteristics at different temperatures are an indirect method to analyse the impact of the electronic structure in the charge transfer process, but here we have collected new spectroscopic evidence by the combination of UPS and XPS to directly trace the modifications of the work function caused by the oxidation process in phosphorene.…”

Análisis DFT de fosforeno y fosforeno oxidado como materiales adsorbentes de Cu2+ a partir de una solución acuosa

“…Se estudió el efecto de la oxidación del fosforeno en la adsorción de Cu 2+ , para cuyo análisis se construyen sistemas en que los átomos de oxígeno se pueden intercalar en el fosforeno, los oxígenos adsorbidos se pueden superponer a un átomo de fósforo o intercalarse en los sitios intersticiales. Algunos resultados previos muestran que los sitios más favorables para la adsorción de los átomos de oxígeno es la posición 'sobre' (Gómez-Pérez, et al, 2020). Sin embargo, con la temperatura y el incremento de la concentración, tanto los resultados experimentales como los teóricos muestran que el fosforeno oxidado contiene una combinación de sitios 'sobre' e intersticiales.…”

Hexagonal Boron Nitride Nanosheets Protect Exfoliated Black Phosphorus Layers from Ambient Oxidation

“…[7] The bandgap is tunable and depends on a variety of characteristics of the material, including the number of layers. [8] BP can absorb light in a wide wavelength [4] and be applied in optoelectronics in the infrared range. [9] It has been proposed for application in humidity sensors, [10,11] electrochemical sensors, [12] and gas sensors.…”