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. 2023 Mar 13;13(1):4146.
doi: 10.1038/s41598-023-31102-z.

New insights into APCVD grown monolayer MoS2 using time-domain terahertz spectroscopy

Saloni Sharma  1   2 , Pooja Chauhan  1   2 , Shreeya Rane  3 , Utkarsh Raj  1 , Shubhda Srivastava  1 , Z A Ansari  4 , Dibakar Roy Chowdhury  3 , Bipin Kumar Gupta  5   6
Affiliations

New insights into APCVD grown monolayer MoS2 using time-domain terahertz spectroscopy

Saloni Sharma et al. Sci Rep. .

Abstract

In modern era, wireless communications at ultrafast speed are need of the hour and search for its solution through cutting edge sciences is a new perspective. To address this issue, the data rates in order of terabits per second (TBPS) could be a key step for the realization of emerging sixth generation (6G) networks utilizing terahertz (THz) frequency regime. In this context, new class of transition metal dichalcogenides (TMDs) have been introduced as potential candidates for future generation wireless THz technology. Herein, a strategy has been adopted to synthesize high-quality monolayer of molybdenum di-sulfide (MoS2) using indigenously developed atmospheric pressure chemical vapor deposition (APCVD) set-up. Further, the time-domain transmission and sheet conductivity were studied as well as a plausible mechanism of terahertz response for monolayer MoS2 has been proposed and compared with bulk MoS2. Hence, the obtained results set a stepping stone to employ the monolayer MoS2 as potential quantum materials benefitting the next generation terahertz communication devices.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1
Figure 1
Pictorial representations of (a) Indigenously laboratory developed APCVD setup for synthesis of monolayer MoS2. (b) Horizontal split furnace and quartz tube. (c) Arrangement of precursors and substrate inside the furnace at constant heating zone before growth and (d) after growth.
Figure 2
Figure 2
Optical and FESEM  Characterizations. (a–c) Optical images. (d–f) FESEM images at different magnifications of APCVD grown monolayer MoS2 over a 300 nm thick Si/SiO2 substrate, scale bar is mentioned.
Figure 3
Figure 3
Raman spectra and Raman mapping. (a) Raman spectra of triangular shaped monolayer MoS2 on 300 nm thick SiO2/Si substrate at three of its corners represented with their frequency difference of in and out of plane vibration modes. Raman mapping of triangular shaped monolayer MoS2with respect to vibrational peak intensity. (b) In plane E12g. (c) Out of plane A1g, scale bar is mentioned.
Figure 4
Figure 4
PL Characterization and Mechanism. (a) PL spectrum of monolayer MoS2 over 300 nm thick SiO2/Si substrate. (b) Deconvoluted PL spectrum of monolayer MoS2. (c) Proposed energy level diagram. (d) PL mapping of monolayer MoS2 with respect to A excitonic peak, scale bar is mentioned.
Figure 5
Figure 5
Time-domain terahertz spectroscopy set-up. (a) Pictorial view of Time-domain terahertz spectroscopy system and insets show the arrangement of parabolic mirrors and sample holder. (b) Schematic representation of THz-TDS mechanism.
Figure 6
Figure 6
Time-domain terahertz spectroscopy. (a) THz signal transmitted through monolayer MoS2 on sapphire substrate. (b) Magnified view of transmitted THz pulse. (c) Transmitted THz amplitude through monolayer MoS2 grown on sapphire substrate. (d) Extracted sheet conductivity of monolayer MoS2 on sapphire substrate in THz frequency domain.
Figure 7
Figure 7
Comparative study of THz characteristics of bulk and monolayer MoS2. (a) THz signal incident on bulk MoS2. (b) THz signal transmitted through bulk MoS2. (c) Energy level diagram of bulk MoS2. (d) THz signal incident on monolayer MoS2. (e) THz signal transmitted through monolayer MoS2. (f) Energy level diagram of monolayer MoS2.
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