Electrical Transport Properties of Polycrystalline Monolayer Molybdenum Disulfide

Abstract

Semiconducting MoS2 monolayers have shown many promising electrical properties, and the inevitable polycrystallinity in synthetic, large-area films renders understanding the effect of structural defects, such as grain boundaries (GBs, or line-defects in two-dimensional materials), essential. In this work, we first examine the role of GBs in the electrical-transport properties of MoS2 monolayers with varying line-defect densities. We reveal a systematic degradation of electrical characteristics as the line-defect density increases. The two common MoS2 GB types and their specific roles are further examined, and we find that only tilt GBs have a considerable effect on the MoS2 electrical properties. By examining the electronic states and sources of disorder using temperature-dependent transport studies, we adopt the Anderson model for disordered systems to explain the observed transport behaviors in different temperature regimes. Our results elucidate the roles played by GBs in different scenarios and give insights into their underlying scattering mechanisms.

High-quality synthetic 2D transition metal dichalcogenide semiconductors

“…1c. In stark contrast to previous studies by Najmaei et al [6], where a 50% degradation in mobility was seen as the channel length was increased from 3µm to 30 µm, we see no degradation of the mobility with increasing channel length, with the longest ~80 µm long segment showing the same mobility as the shortest (~4µm long), within the measurement error. We estimate that there are ~16 junctions between single crystals along the length of the 82 µm long channel.…”

Controlled synthesis of high-quality crystals of monolayer MoS2 for nanoelectronic device application

“…These excellent electronic properties further confirm that the as-grown monolayer MoS 2 triangles are nearly perfect single crystals in high uniformity because there are few grain boundaries or other defects scattering the carriers while transporting [31].…”

“…Synthesis of large-area MoS 2 films have been reported in the past few years [22][23][24][25][26][27]. However, the preparation of large-size monolayer MoS 2 single crystals remain to be improved in view of its superior electronic and optoelectronic characteristics [28][29][30][31]. Furthermore, as the size of MoS 2 single crystals increased to hundreds of micrometers, the device fabrication and modulation process would be simplified greatly.…”

The Effect of Twin Grain Boundary Tuned by Temperature on the Electrical Transport Properties of Monolayer MoS2

“…The observed behavior is common in highly-disordered systems and a signature of hopping transport via localized states [29][30][31]. The VRH transport is found to be consistent with the larger electrical conductivity of GB, due to localized mid-gap states that arises from twin GB can increase the hopping bond and conductivity [15,16,32,33].…”