Seeded growth of highly crystalline molybdenum disulphide monolayers at controlled locations

Abstract

Monolayer transition metal dichalcogenides are materials with an atomic structure complementary to graphene but diverse properties, including direct energy bandgaps, which makes them intriguing candidates for optoelectronic devices. Various approaches have been demonstrated for the growth of molybdenum disulphide (MoS 2 ) on insulating substrates, but to date, growth of isolated crystalline flakes has been demonstrated at random locations only. Here we use patterned seeds of molybdenum source material to grow flakes of MoS 2 at predetermined locations with micrometre-scale resolution. MoS 2 flakes are predominantly monolayers with high material quality, as confirmed by atomic force microscopy, transmission electron microscopy and Raman and photoluminescence spectroscopy. As the monolayer flakes are isolated at predetermined locations, transistor fabrication requires only a single lithographic step. Device measurements exhibit carrier mobility and on/off ratio that exceed 10 cm 2 V À 1 s À 1 and 10 6 , respectively. The technique provides a path for in-depth physical analysis of monolayer MoS 2 and fabrication of MoS 2 -based integrated circuits.

Electrolytic phototransistor based on graphene-MoS2 van der Waals p-n heterojunction with tunable photoresponse

“…The recent studies of growth concerning various 2D materials [14][15][16][17] has opened the possibility to design van der Waals (vdW) heterostructures using graphene as an underlayer, which provides more opportunities for achieving desired electronic or optoelectronic properties 3,[18][19][20][21][22][23][24] . In fact even if graphene has exceptionally high mobility at room temperature, for optoelectronics 9 the overall low absorption of a single carbon layer (≈ 2%) and the absence of band gap implies that graphene needs to be combined with some semiconductor compounds.…”

MoS2 based dual input logic AND gate

“…12,18 In a typical transfer process, the original substrate with MoS 2 crystals is spun coated (4000 rpm/45 s) with PMMA and then immersed in a KOH (0.1M) solution. The SiO 2 layer is slowly dissolved by KOH and the PMMA film with the MoS 2 is washed with water and transferred on to the split gate FET substrate and dried.…”

“…The charge mobility in these materials exceed 200 cm 2 /V-s for exfoliated MoS 2 13-15 and ∼ 10 cm 2 /V-s for CVD grown MoS 2 on SiO 2 substrates. 8,10,12 Being a stable n-type semiconductor, MoS 2 has potentially wide range of applications in the fields of nanoelectronics (FET, diodes) and energy harvesting (photovoltaics, solar cells). An important electronic device for practical applications is a FET, since it forms the basic building block in logic circuits and switches for displays and is thus widely studied using organic and inorganic semiconducting materials.…”

“…1,2 Monolayers can be obtained via exfoliation of macroscopic MoS 2 crystals [3][4][5][6] or via chemical vapor deposition (CVD) of selected Mo containing compounds in a gaseous sulfur rich environment. [7][8][9][10][11][12] Pristine MoS 2 is a n-type semiconductor typically characterized in a field effect transistor (FET) configuration with a global gate potential that is responsible for the transistor action. The charge mobility in these materials exceed 200 cm 2 /V-s for exfoliated MoS 2 13-15 and ∼ 10 cm 2 /V-s for CVD grown MoS 2 on SiO 2 substrates.…”

Progress on Crystal Growth of Two-Dimensional Semiconductors for Optoelectronic Applications

“…Although wafer-scale uniformity could be achieved in various synthesis methods as discussed above, the growth of high-quality large-area single crystal thin film is still the main challenge for further nanoelectronic applications of TMDCs. Han et al reported an alternative approach, in which the deposition of a seed layer enables selective growth of single crystalline TMDCs at controlled spatial locations (shown in Figure 3o) [71]. This provides more insight on the growth mechanism of TMDCs and the potential solution towards high-quality large-area TMDC thin film growth for optoelectronic applications.…”