Using in-situ Raman scattering from phosphorene channel in an electrochemically top-gated field effect transistor, we show that its phonons with Ag symmetry depend much more strongly on concentration of electrons than that of holes, while the phonons with Bg symmetry are insensitive to doping. With first-principles theoretical analysis, we show that the observed electon-hole asymmetry arises from the radically different constitution of its conduction and valence bands involving π and σ bonding states respectively, whose symmetry permits coupling with only the phonons that preserve the lattice symmetry. Thus, Raman spectroscopy is a non-invasive tool for measuring electron concentration in phosphorene-based nanoelectronic devices.
@article{arxiv.1603.02941,
title = {Electron-Hole Asymmetry in the Electron-phonon Coupling in Top-gated Phosphorene Transistor},
author = {Biswanath Chakraborty and Satyendra Nath Gupta and Anjali Singh and Manabendra Kuiri and Chandan Kumar and D. V. S. Muthu and Anindya Das and U. V. Waghmare and A. K. Sood},
journal= {arXiv preprint arXiv:1603.02941},
year = {2016}
}