Atomic Step-Promoted\nGrowth and Interfacial Coupling\nin MoS<sub>2</sub>/TMO Heterostructures

The interfacial structural coupling, electronic transfer,\nand particle\ncoupling behaviors in heterojunctions composed of transition metal\noxides (TMOs) and transition metal dichalcogenides (TMDCs) can profoundly\naffect the original lattice structures, charge dynamics, and spin\ndegrees of freedom, potentially leading to novel physicochemical phenomena\nand the elucidation of new physical mechanisms. However, the control\nof interface quality in such systems is often neglected, which can\ncompromise the functionality of these heterojunctions. There is a\nnotable paucity of direct research evidence regarding how the surface\nstructure control of TMO single crystals influences the synthesis\nand properties of TMDCs. In this study, we have selected Al<sub>2</sub>O<sub>3</sub>(0001), TiO<sub>2</sub>(110), and SrTiO<sub>3</sub>(111)\nas representative TMO substrates. Through precise etching and annealing\ntreatments, we achieved atomically flat stepped surfaces on these\nsubstrates. Subsequently, we investigated the impact of these ordered\natomic steps on the chemical vapor deposition (CVD) growth of MoS<sub>2</sub>, comparing them with the disordered surfaces of untreated\nsingle crystals. Furthermore, we utilized the polarized negative excitons\nin the SrTiO<sub>3</sub>/MoS<sub>2</sub> composite system as a probe\nto explore the extent of polarization coupling under varying interfacial\nconditions. This research aims to underscore the critical importance\nof interfacial orderliness of oxide single crystal surfaces in modulating\nthe growth of TMDCs and their interactions with TMOs. By highlighting\nthe significance of interface orderliness, we seek to advance the\nunderstanding of effective interfacial interactions in these composite\nsystems.