Complete quasi-direct excitonic emissions in few-layered ZrS3

Adzilah Shahna Rosyadi^1*, Ching Hwa Ho¹

¹Graduate Institute of Applied Science and Technology, NTUST, Taipei city, Taiwan

* Presenter:Adzilah Shahna Rosyadi, email:D10922801@mail.ntust.edu.tw

Strong in-plane structural anisotropy exists in a small number of materials such as black phophorus, ReS2, ReSe2 and TMTCs. However, the optical studies on the pseudo-1D material of ZrS3 still need to be expanded as the band structure and excitonic transition are not well understood. Due to the indirect bandgap nature of ZrS3, it is challenging to present the strong emission from direct bandgap. Here, we present our results of strong emission photoluminescence at Ax= 1.94 eV at T=300K which is similar to the thermoreflectance for bandgap measurement due to direct emission. We confirm the photoluminescence with center wavelength 639 nm is a quasi-direct transition as its transmittance revealed the indirect part is only 0.08 eV difference detected with the quasi-direct bandgap. The anisotropic behavior strongly affected the excitonic transitions as the sample b-axis direction rotated toward parallel and perpendicular to the polarized light. Time-resolved photoluminescence (TRPL) was studied to determine the decay time of the excitons around 1= 0.296 ± 0.012 ns.

Keywords: Anisotropy, TMTCs, TRPL, Zirconium trisulphide , semiconductor