Controlled growth of two-dimensional InAs single crystals via van der Waals epitaxy

Two-dimensional(2D)indium arsenide(InAs)is promising for future electronic and optoelectronic applications such as highperformance nanoscale transistors,flexible and wearable devices,and high-sensitivity broadband photodetectors,and is advantageous for its heterogeneous integration with Si-based electronics.However,the synthesis of 2D InAs single crystals is challenging because of the nonlayered structure.Here we report the van der Waals epitaxy of 2D InAs single crystals,with their thickness down to 4.8 nm,and their lateral sizes up to~37μm.The as-grown InAs flakes have high crystalline quality and are homogenous.The thickness can be tuned by growth time and temperature.Moreover,we explore the thickness-dependent optical properties of InAs flakes.Transports measurement reveals that 2D InAs possesses high conductivity and high carrier mobility.Our work introduces InAs to 2D materials family and paves the way for applying 2D InAs in high-performance electronics and optoelectronics.

Tribocorrosion Behavior and Degradation Mechanism of 316L Stainless Steel in Alkaline Solution:Effect of Tribo-Film

Tribocorrosion behavior and degradation mechanism of 316L stainless steel(SS)in alkaline solution were studied.The SS was worn in 0.1 mol/L NaOH solution with different potentials to investigate the synergism between wear and corrosion.The SS showed larger material loss at a cathodic potential of-0.8 V and lower material loss at anodic potential when compared with that under pure wear condition.This was inverse when compared with that in other corrosive media,such as H_(2)SO_(4)and NaCl solutions.The formation of Tribo-films with different properties at different potentials played decisive role in the degradation process.Tribo-films were formed at cathodic potential(-0.8 V)and anodic potentials(0 and 0.4 V).The tribo-film formed at-0.8 V had the highest O content and was very brittle.It resulted in the easily peeling off of the film and then the acceleration of material degradation.By contrast,the Tribo-films formed at anodic potentials were more complete and the O content was much lower.Such kind of ductile Tribo-films could protect the SS from wear.The locally high concentration of OH-produced in the reduction reaction of oxygen at-0.8 V could react with the tribo-film which consist of nano-particles(NPs)with high chemical activity and finally led to deep oxidation and embrittlement of the film.The passivation of the NPs at the anodic potentials could inhibit the oxidation of tribo-film to maintain its ductility.