Unambiguous identification of monolayer phosphorene by phase-shifting   interferometry
  Monolayer phosphorene provides a unique two-dimensional (2D) platform to investigate the fundamental many-body interactions. However, owing to its high instability, unambiguous identification of monolayer phosphorene has been elusive. Consequently, many important fundamental properties, such as exciton dynamics, remain underexplored. We report a rapid, noninvasive, and highly accurate approach based on optical interferometry to determine the layer number of phosphorene, and confirm the results with reliable photoluminescence measurements. Based on the measured optical gap and the calculated electronic energy gap, we determined the exciton binding energy to be ~0.4 eV for the monolayer phosphorene on SiO2/Si substrate, which agrees well with theoretical predictions. Our results open new avenues for exploring fundamental phenomena and novel optoelectronic applications using monolayer phosphorene. 
Jiong Yang, Renjing Xu, Jiajie Pei, Ye Win Myint, Fan Wang, Zhu Wang,   Shuang Zhang, Zongfu Yu, and Yuerui Lu
cond-mat.mtrl-sci