Wafer-Scale Growth of Single-Crystal 2D Semiconductor on Perovskite Oxides for High-Performance Transistors

Abstract

Emerging two-dimensional (2D) semiconducting materials serve as promising alternatives for next-generation digital electronics and optoelectronics. However, large-scale 2D semiconductor films synthesized so far are typically polycrystalline with defective grain boundaries that could degrade their performance. Here, for the first time, wafer-size growth of a single-crystal Bi 2 O 2 Se film, which is a novel air-stable 2D semiconductor with high mobility, was achieved on insulating perovskite oxide substrates [SrTiO 3 , LaAlO 3 , (La, Sr)(Al, Ta)O 3 ]. The layered Bi 2 O 2 Se epilayer exhibits perfect lattice matching and strong interaction with perovskite oxide substrates, which enable unidirectional alignment and seamless mergence of multiple seeds into single-crystal continuous films free of detrimental grain boundaries. The single-crystal Bi 2 O 2 Se thin films show excellent spatial homogeneity over the entire wafer and allow for the batch fabrication of high-performance field-effect devices with high mobilities of ∼150 cm 2 V −1 s −1 at room temperature, excellent switching behavior with large on/off ratio of >10 5 , and high drive current of ∼45 μA μm −1 at a channel length of ∼5 μm. Our work makes a step toward the practical applications of high-mobility semiconducting 2D layered materials and provides an alternative platform of oxide heterostructure to investigate novel physical phenomena.

Molecular Beam Epitaxy and Electronic Structure of Atomically Thin Oxyselenide Films

“…Oxychalcogenides, which can be regarded as mixing and bridging chalcogenides and oxides together, reactivate their research booms for the remarkable phenomena such as high carrier mobility, [9] thermoelectricity, [10][11][12] ferroelectricity, [13] and superconductivity. [2,9,13,[15][16][17][18][19][20][21][22][23] For example, the bulk Bi 2 O 2 Se crystals show an ultrahigh Hall mobility of ≈280 000 cm 2 V −1 s −1 at low temperature [9] and robust bandgap (immune to Se vacancies) after cleavage. [2,9,13,[15][16][17][18][19][20][21][22][23] For example, the bulk Bi 2 O 2 Se crystals show an ultrahigh Hall mobility of ≈280 000 cm 2 V −1 s −1 at low temperature [9] and robust bandgap (immune to Se vacancies) after cleavage.…”

“…[14] Bi 2 O 2 Se, a representative of oxychalcogenides family, emerged as an air-stable highmobility layered semiconductor, which holds promise for next-generation digital devices and optoelectronics. [17] Nanoplates and thin films of Bi 2 O 2 Se were successfully prepared by chemical vapor deposition (CVD), [9,15,21,23] displaying excellent switching behavior of I on /I off and high Hall mobility (up to 450 cm 2 V −1 s −1 ) at room temperature. [17] Nanoplates and thin films of Bi 2 O 2 Se were successfully prepared by chemical vapor deposition (CVD), [9,15,21,23] displaying excellent switching behavior of I on /I off and high Hall mobility (up to 450 cm 2 V −1 s −1 ) at room temperature.…”

Vapor‐phase growth of high‐quality wafer‐scale two‐dimensional materials

“…The most prevailing one is to suppress nucleation or even allow only one nucleus to grow into a wafer‐scale 2D film . Another vital approach is to “seamless stitch” multiple aligned islands into single‐crystal 2D materials over wafer scale . The third one is triggering the ESG to achieve the nearly single‐crystal 2D materials .…”

“…Their practical applications in high‐performance electronics and optoelectronics, such as touch screen, radio frequency devices, photovoltaic devices, solar cell, and so on, are hampered by their poor crystalline quality and limited size. Wafer‐scale and high‐quality 2D materials with few or even without grain boundaries will exhibit excellent electronic performance with high charge mobility, and low interface scattering, which is beneficial in modern electronics . Therefore, routes toward the synthesis of high‐quality (especially single‐crystal) wafer‐scale 2D materials that are compatible with current semiconductor microfabrication processes are essential for exploring the full potential of them in the practical applications.…”

“…A straightforward route is to grow up from a single seed, which is similar to silicon ingot growth . Another thoroughgoing approach is to make the multinucleation domains with identical orientation seamless coalesce into a wafer‐scale single‐crystal film, which can usually be achieved on a single‐crystal substrate or liquid substrate . The third effective one is the evolutionary selection growth (ESG) that can eliminate the formation of undesired seeds to get large‐area single‐crystal 2D materials, even on a polycrystalline substrate .…”