Single-Layer MoS₂ Grown on Atomically Flat SrTiO₃ Single Crystal for Enhanced Trionic Luminescence

Abstract

The elaborate interface interactions can be critical in determining the achievable functionality of a semiconductor heterojunction (SH), particularly when two-dimensional material is enclosed in the system and its thickness is at an atomic extreme. In this work, we have successfully constructed a SH model system composed of typical transition-metal chalcogenide (TMDs) and transition metal oxides (TMO) by directly growing molybdenum sulfide (MoS2) nanosheets on atomically flat strontium titanate (SrTiO3) single crystal substrates through a conventional chemical vapor deposition (CVD) synthetic method. Multiple measurements have demonstrated the uniform monolayer thickness and single crystallinity of the MoS2 nanosheets as well as the atomic flatness of the heterojunction surface, both characterizing an extremely high quality of the interface. Clear evidence have been obtained for the electron transfer from the MoS2 adlayer to the SrTiO3 substrate which varies against the interface conditions. More importantly, the photoluminescence of MoS2 is significantly tailored, which is correlated with both the cleanness of the interface and the crystal orientation of the SrTiO3 substrate. These results not only shed fresh lights on the structure–property relationship of the TMDs/TMO heterostructures but also manifest the importance of the ideal interface structure for a hybridized system.

Modulated Photoluminescence of Single‐Layer MoS2 via Nanostructured SrTiO3 Surface

“…Applying the Tr‐STO substrate to the CVD process as reported, [ 45,55 ] we successfully grew high quality MoS 2 nanosheets with uniform triangular shape, as shown by the SEM image in Figure 1c as well as the AFM topographic image in Figure 1d (see Figure S4, Supporting Information for the corresponding phase image). Similar results on the relatively flatter substrate with lower steps are supplied in Figure S5 (Supporting Information).…”

“…Their difference of 19.1 cm –1 also falls in the region for SL‐MoS 2 (<20 cm −1 ). [ 24,45 ] With all these detailed characterizations, we can safely conclude that high quality SL‐MoS 2 nanosheets have been successfully synthesized on the Tr‐STO substrate. More importantly, the as‐grown SL‐MoS 2 intimately attaches to the trenches of the SrTiO 3 surface, thus constructing an ideal model system to investigate the morphological effects of the hybridized system.…”

“…[ 56,57 ] Moreover, Raman spectroscopy was also applied to evaluate the crystallinity and thickness of the as‐grown MoS 2 . As reported in our previous work, [ 45 ] it is difficult to directly identify the Raman vibrations of the MoS 2 adlayer due to the background contribution of the SrTiO 3 substrate (Figure S6, Supporting Information). Alternatively, Figure S7 (Supporting Information)shows the Raman spectrum taken over the sample prepared by transferring the as‐grown MoS 2 onto a SiO 2 /Si substrate.…”

2D Ultrawide Bandgap Semiconductors: Odyssey and Challenges

“…Successful exfoliation of graphene [38] in 2004 has tremendously boosted research on various 2D materials, including transition metal dichalcogenides (TMDs), [39][40][41][42][43][44][45] black phosphorous (b-P), [46][47][48] black arsenic (b-As), [49,50] phosphorous compounds, [51,52] hexagonal boron nitride (h-BN), [53][54][55][56] and Mxene. [57] Compared to devices based on narrow bandgap semiconductors, ultraviolet photodetectors based on 2D UWBG semiconductors need not costly high-pass optical filters to block out visible and infrared photons and without cooled to reduce dark current, leading to a significant loss of effective area of the system.…”

“…[19][20][21][22][23] However, in the post-Moore era, the traditional UWBG semiconductor devices with large size, high power and high cost cannot meet the future requirements of high-performance (opto)electronic devices. [24,25] In this regard, desingings of low-dimensional semiconductor material systems with novel structure and good adaptability have become a research hotspot.Successful exfoliation of graphene [38] in 2004 has tremendously boosted research on various 2D materials, including transition metal dichalcogenides (TMDs), [39][40][41][42][43][44][45] black phosphorous (b-P), [46][47][48] black arsenic (b-As), [49,50] phosphorous compounds, [51,52] hexagonal boron nitride (h-BN), [53][54][55][56] and Mxene. [57] Compared to devices based on narrow bandgap semiconductors, ultraviolet photodetectors based on 2D UWBG semiconductors need not costly high-pass optical filters to block out visible and infrared photons and without cooled to reduce dark current, leading to a significant loss of effective area of the system.…”