TY - JOUR
T1 - Exciton and trion dynamics in atomically thin MoSe2 and WSe2
T2 - Effect of localization
AU - Godde, T.
AU - Schmidt, D.
AU - Schmutzler, J.
AU - Aßmann, M.
AU - Debus, J.
AU - Withers, F.
AU - Alexeev, E. M.
AU - Del Pozo-Zamudio, O.
AU - Skrypka, O. V.
AU - Novoselov, K. S.
AU - Bayer, M.
AU - Tartakovskii, A. I.
PY - 2016/10/5
Y1 - 2016/10/5
N2 - We present a detailed investigation of the exciton and trion dynamics in naturally doped MoSe2 and WSe2 single atomic layers as a function of temperature in the range 10-300 K under above band-gap laser excitation. By combining time-integrated and time-resolved photoluminescence (PL) spectroscopy, we show the importance of exciton and trion localization in both materials at low temperatures. We also reveal the transition to delocalized exciton complexes at higher temperatures where the exciton and trion thermal energy exceeds the typical localization energy. This is accompanied by strong changes in PL including suppression of the trion PL and decrease of the trion PL lifetime, as well as significant changes for neutral excitons in the temperature dependence of the PL intensity and the appearance of a pronounced slow PL decay component. In MoSe2 and WSe2 studied here, the temperatures where such strong changes occur are observed at around 100 and 200 K, respectively, in agreement with their inhomogeneous PL linewidth of 8 and 20 meV at T≈10K. The observed behavior is a result of a complex interplay between influences of the specific energy ordering of bright and dark excitons in MoSe2 and WSe2, sample doping, trion, and exciton localization and various temperature-dependent nonradiative processes.
AB - We present a detailed investigation of the exciton and trion dynamics in naturally doped MoSe2 and WSe2 single atomic layers as a function of temperature in the range 10-300 K under above band-gap laser excitation. By combining time-integrated and time-resolved photoluminescence (PL) spectroscopy, we show the importance of exciton and trion localization in both materials at low temperatures. We also reveal the transition to delocalized exciton complexes at higher temperatures where the exciton and trion thermal energy exceeds the typical localization energy. This is accompanied by strong changes in PL including suppression of the trion PL and decrease of the trion PL lifetime, as well as significant changes for neutral excitons in the temperature dependence of the PL intensity and the appearance of a pronounced slow PL decay component. In MoSe2 and WSe2 studied here, the temperatures where such strong changes occur are observed at around 100 and 200 K, respectively, in agreement with their inhomogeneous PL linewidth of 8 and 20 meV at T≈10K. The observed behavior is a result of a complex interplay between influences of the specific energy ordering of bright and dark excitons in MoSe2 and WSe2, sample doping, trion, and exciton localization and various temperature-dependent nonradiative processes.
UR - http://www.scopus.com/inward/record.url?scp=84992048113&partnerID=8YFLogxK
U2 - 10.1103/PhysRevB.94.165301
DO - 10.1103/PhysRevB.94.165301
M3 - Article
AN - SCOPUS:84992048113
SN - 1098-0121
VL - 94
JO - Physical Review B - Condensed Matter and Materials Physics
JF - Physical Review B - Condensed Matter and Materials Physics
IS - 16
M1 - 165301
ER -