Open AccessThickness Scaling Effects on the Complex Optical Conductivity of Few‐Layer WSe 2 Investigated by Spectroscopic Ellipsometry
Author(s) -
Fang Mingsheng,
Gu Honggang,
Song Baokun,
Guo Zhengfeng,
Liu Shiyuan
Publication year - 2022
Publication title -
advanced photonics research
Language(s) - English
Resource type - Journals
ISSN - 2699-9293
DOI - 10.1002/adpr.202100299
Subject(s) - exciton , ellipsometry , materials science , conductivity , scaling , optical conductivity , band gap , layer (electronics) , spectral line , optoelectronics , photonics , nanoelectronics , molecular physics , optics , condensed matter physics , physics , thin film , nanotechnology , geometry , mathematics , quantum mechanics , astronomy
2D WSe 2 have attracted widespread attentions as an ideal platform for new type optoelectronic and nanoelectronics applications. Understanding the intrinsic thickness scaling effects in complex optical conductivity of 2D, WSe 2 is vital for WSe 2 ‐based photonic and optoelectronic devices. Herein, complex optical conductivities of 1–5 layers in the energy range of 0.73–6.42 eV by spectroscopic ellipsometry with the classical slab model have been determined. Up to eight feature peaks (A–H) are observed in the optical conductivity spectra, and the central energies of these peaks are identified by the differential spectrum analysis method. These central energies exhibit interesting layer dependencies due to the thickness scaling effects. Specifically, for the low‐energy feature peaks A–E, their central energies decrease with the thickness increasing. But for the high‐energy feature peaks G and H, their central energies first show significant blueshifts and then redshifts as the thickness increases. These novel layer‐dependent evolvements are attributed in the optical conductivity of few‐layer WSe 2 to the competition mechanism between the decreasing exciton binding energy and the band gap narrowing.