Periodical Ripening for MOCVD Growth of Large 2D Transition Metal Dichalcogenide Domains

Abstract

2D semiconductors, especially 2D transition metal dichalcogenides (TMDCs), have attracted ever-growing attention toward extending Moore's law beyond silicon. Metal-organic chemical vapor deposition (MOCVD) has been widely considered as a scalable technique to achieve wafer-scale TMDC films for applications. However, current MOCVD process usually suffers from small domain size with only hundreds of nanometers, in which dense grain boundary defects degrade the crystalline quality of the films. Here, a periodical varyingtemperature ripening (PVTR) process is demonstrated to grow wafer-scale high crystalline TMDC films by MOCVD. It is found that the high-temperature ripening significantly reduces the nucleation density and therefore enables single-crystal domain size over 20 µm. In this process, no additives or etchants are involved, which facilitates low impurity concentration in the grown films. Atom-resolved electron microscopy imaging, variable temperature photoluminescence (PL) spectroscopy, and electrical transport results further confirm comparable crystalline quality to those observed in mechanically exfoliated TMDC films. The research provides a scalable route to produce high-quality 2D semiconducting films for applications in electronics and optoelectronics.

Silver nanowire electrodes for transparent light emitting devices based on WS2 monolayers

“…For MOCVD-grown TMDCs, the low internal quantum yield, measured here to be in the order of 10 −4 for the WS 2 used for device fabrication (see supplementary figure S1), is currently a limiting factor. It is expected that high defect densities are present in TMDCs grown via MOCVD [60][61][62], limiting the quantum yield due to non-radiative recombination [63]. Low temperature PL analysis revealed distinct defect related emission, supporting this hypothesis [18].…”

Diffusion Control on the Van der Waals Surface of Monolayers for Uniform Bi‐Layer MoS2 Growth

“…To further evaluate the device performances of the bi-layer MoS 2 FETs, we benchmark the electron mobility and on/off ratio of the bi-layer MoS 2 FETs with previously reported FET devices fabricated using MoS 2 grown by MOCVD (Figure 6h and Table 1). [4,28,36,45,46,49,[65][66][67][68][69][70][71] Our bi-layer MoS 2 FETs demonstrate outstanding device performances in both mobility and on/off ratio. Although our bi-layer MoS 2 FETs with Ti contacts shows lower device performances compared to single-crystal bi-layer MoS 2 grown through epitaxial growth, it shows the highest electron mobility among the existing reports involving MoS 2 grown by MOCVD.…”

2D Materials in Flexible Electronics: Recent Advances and Future Prospectives

“…It is worth noting that by using an amorphous SiO 2 surface as the substrate, only polycrystalline TMD films with randomly aligned domains have been synthesized. − To produce wafer-scale single-crystal TMDs, one approach is to initiate a single nucleus on a larger substrate and grow it into a single crystal. However, controlling the nucleation densities of TMDs on polycrystalline or amorphous substrates can be challenging.…”