Quantitative Tracking of the Oxidation of Black Phosphorus in the Few-Layer Regime

Abstract

Previous theoretical reports have described the oxidation of few-layer black phosphorus and its effects on the electronic properties. Theoretically, native oxide layers bring opportunities for band gap engineering, but the detection of the different types of oxides is still a challenge at the experimental level. In this work, we uncover a correlation between thermal processes and Raman shift for the A g 1 , B 2g , and A g 2 vibrational modes. The thermal expansion coefficients (temperature range, 290–485 K) for the A g 1 , B 2g , and A g 2 were −0.015, −0.027, and −0.028 cm –1 K –1 , respectively. Differential scanning calorimetry analysis shows an endothermic process centered at 528 K, and it was related with a mass increase according to thermogravimetric analysis. Raman shift temperature dependence was correlated to theoretical lattice thermal expansion, and a significant deviation was detected in the stacking direction at 500 K.

Experimental studies on the exfoliation and oxidation behavior of few-layers black phosphorus

“…The surface oxides are the primary outcome of the few-layers black phosphorus oxidation and the transition to the planar configuration requires additional energy. The surface to planar transition starts at 373 K in agreement with the thermally activated electric conduction measurements and previous results 172 . This phosphorene oxide transition temperature is yet another operational limit to be considered in future applications of exfoliated black phosphorus, as the electronic structure is modified and can alter the response of transducer applications.…”

“…The surface oxide has been proposed as an electronically Finally, the formation of metastable black phosphorus oxides has been reported for liquid phase exfoliation 103,109 . In this work, we have proved that the electronic structure transformation is caused by oxidation processes and related the results with a recent work 172 .…”

“…The Raman characterization (Figure 37c) indicates a ratio A 1 g/A 2 g = 0.65, which indicates a slight oxidation according to recent literature 31,45 . Correspondingly, the increase of the electrical resistance can be explained by the Experimental studies on the exfoliation and oxidation behavior of few-layers black phosphorus 74 reconfiguration process as it is localized at the same temperature as the endothermic process, mass increase by the incorporation of physisorbed oxygen and lattice distortions reported recently 172 . It should be noted that since our I-V measurements were performed in inert (Ar)…”

“…We proved that the activation energy for thermally activated electric conduction a good quantitative measure of oxidation processes 172 . The methodology shown here could be useful The Raman spectral features applicable for the identification of the few-layers black phosphorus were debated and the blueshift of the Raman-active vibrational modes was not Experimental studies on the exfoliation and oxidation behavior of few-layers black phosphorus 85 fully accepted in the literature.…”

“…Taking advantage of the crystallographically oriented vibrational modes and the strong anisotropy of black phosphorus, it was possible to determine the phase transition temperature between surface oxides and planar oxides for the first time in literature. The lattice deformation of few-layers black phosphorus by oxidation was studied in several computational works, but our work 172 was the first experimental study to take advantage of this phenomenon to characterize the oxidation process.…”