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

摘要

2D semiconductors, especially 2D transition metal dichalcogenides (TMDCs),have attracted ever-growing attention toward extending Moore's law beyondsilicon. Metal–organic chemical vapor deposition (MOCVD) has been widelyconsidered as a scalable technique to achieve wafer-scale TMDC films forapplications. However, current MOCVD process usually suffers from smalldomain size with only hundreds of nanometers, in which dense grain boundarydefects degrade the crystalline quality of the films. Here, a periodical varyingtemperatureripening (PVTR) process is demonstrated to grow wafer-scalehigh crystalline TMDC films by MOCVD. It is found that the high-temperatureripening significantly reduces the nucleation density and therefore enablessingle-crystal domain size over 20 μm. In this process, no additives or etchantsare 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 confirmcomparable crystalline quality to those observed in mechanically exfoliatedTMDC films. The research provides a scalable route to produce high-quality 2Dsemiconducting films for applications in electronics and optoelectronics.