Abstract
We present a theory to address the photoluminescence (PL) intensity and valley polarization (VP) dynamics in monolayer WSe2, under the impact of excitonic dark states of both excitons and biexcitons. We find that the PL intensity of all excitonic channels including intravalley exciton (Xb), intravalley biexciton (XXk,k) and intervalley biexciton (XX[Formula: see text]) in particular for the XXk,k PL is enhanced by laser excitation fluence. In addition, our results indicate the anomalous temperature dependence of PL, i.e. increasing with temperature, as a result of favored phonon assisted dark-to-bright scatterings at high temperatures. Moreover, we observe that the PL is almost immune to intervalley scatterings, which trigger the exchange of excitonic states between the two valleys. As far as the valley polarization is concerned, we find that the VP of Xb shrinks as temperature increases, exhibiting opposite temperature response to PL, while the intravalley XXk,k VP is found almost independent of temperature. In contrast to both Xb and XXk,k, the intervalley XX[Formula: see text] VP identically vanishes, because of equal populations of excitons in the K and [Formula: see text] valleys bounded to form intervalley biexcitons. Not...Continue Reading
References
Apr 15, 1992·Physical Review. B, Condensed Matter·T SchmidtW Zulehner
Jun 19, 2012·Nature Nanotechnology·Kin Fai MakTony F Heinz
Sep 26, 2012·Physical Review Letters·Di XiaoWang Yao
Feb 14, 2013·Nature Communications·Jason S RossXiaodong Xu
Jul 31, 2013·Physical Review Letters·Yang Song, Hanan Dery
Aug 13, 2013·Nature Nanotechnology·Aaron M JonesXiaodong Xu
May 14, 2014·Nature Communications·Hongyi YuWang Yao
Jun 28, 2014·Science·K F MakP L McEuen
May 23, 2015·Nanoscale·Ashish AroraMarek Potemski
Jan 2, 2016·Physical Review Letters·Xiao-Xiao ZhangTony F Heinz
Mar 2, 2016·Nanoscale·Pramoda K NayakPo-Wen Chiu
Sep 3, 2016·Nature Communications·Gerd PlechingerTobias Korn
Nov 12, 2016·Physical Review Letters·G WangB Urbaszek
Jan 24, 2017·Scientific Reports·Fanyao QuDavid L Azevedo
Apr 7, 2017·Scientific Reports·Mark DanovichVladimir I Fal'ko
Jun 27, 2017·Nature Nanotechnology·Xiao-Xiao ZhangTony F Heinz
Jun 29, 2017·Nature Communications·Kai HaoGalan Moody
Aug 23, 2017·European Journal of Cancer : Official Journal for European Organization for Research and Treatment of Cancer (EORTC) [and] European Association for Cancer Research (EACR)·Cornelia M FockeUNKNOWN German Breast Screening Pathology Initiative
Aug 30, 2017·Nanoscale·Maciej R MolasMarek Potemski