"Band gap engineering" in two-dimensional (2D) materials plays an important role in tailoring their physical and chemical properties. The tuning of the band gap is typically achieved by controlling the composition of the semiconductor alloys.Here, we report the synthesis and electrical properties of...
Here, we examine light emission of monolayer WSe2 using temperature-dependent photoluminescence and time-resolved photoluminescence spectroscopy. We present experimental evidence for the existence of an optically forbidden dark state of the band-gap exciton that lies tens of meV below the o...
Monolayer transition metal dichalcogenides, such as MoS 2 and WSe 2 , have been known as direct gap semiconductors and emerged as new optically active materials for novel device applications. Here we reexamine their direct gap properties by investigating the strain effects on the photoluminescence of...
Both 1 s exciton (1.655 eV) and 2 s excitonic (1.780 eV) absorption features can be seen in Fig. 1c and their spectral positions are labeled by the white arrows. The parabolic features in Fig. 1c arise from the DBR side band. Fig. 1: Reflection spectrum of WSe2 on ...
Band gapPolarizationEpitaxyWe have fabricated a high-quality monolayer WSe2film on bilayer graphene by epitaxial growth and revealed the electronic states by spin- and angle-resolved photoemission spectroscopy. We observed a direct energy gap at the Brillouin-zone corner in contrast to the indirect ...
(a) Strongly bound electron–hole pairs, excitons, dominate optical properties of TMDC monolayers such as WSe2. In WSe2 there exist two different exciton series. The B-exciton is about 400 meV above the A-exciton due to spin-obit splitting of the valence band. (b) Excitons have a ...
A MoSe2/WSe2 heterojunction-based photodetector at tele- communication wavelengths. Adv. Funct. Mater. 28, 1804388 (2018). 19. Bonaccorso, F. & Sun, Z. Solution processing of graphene, topological insu- lators and other 2d crystals for ultrafast photonics. Opt. Mater. Express 4, 63–78...
Because of quantum constraint, as the layers decrease, the band gap of WSe2 increases constantly. When WSe2 is monolayer, the indirect band gap transforms direct band gap. And band gap width is 1.6~1.7 eV [30] Interlamination weak van der Waals force causes great difference of energy band...
The in-plane electric field F(x) inside the WSe2 is shown by the solid black line (right axis). e Band diagram of the p–n junction between x = −0.1 and 0.1 μm (cf., Fig. 1d) calculated for Vasym = −10 V and VB = 0 V. The solid orange lines...
band gap, which turned the p-type into n-type WSe2, as shown in Fig.3c. The tuning of the Fermi level (EF) within the gap that is significantly larger than the previously reported number for Nb-doped MoSe2and NOx-doped WSe214,16implies that it is possible to tune theEFposition ...