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The unique electronic structure of Bi2Se3 makes it appealing not only for studying fundamental topological physics but also for pursuing technological applications that include future electronics, spintronics, and quantum computing. This work uses a chemical vapor deposition approach to synthesize submillimeter domain continuous epitaxial thin films as well as continuous films with preferred orientation and domain sizes ranging up to a millimeter. Atomic force microscopy imaging reveals a terraced pyramid structure with step sizes down to one quintuple layer. We observe that large amounts of deposition on the tube walls from previous growths negatively affect the quality of epitaxy but positively affect grain size due to revaporization of previous growth. Transport measurements and Hikami–Larkin–Nagaoka fits of conductivity versus magnetic field indicate a bulk conducting nature to the film. This work pushes forward the domain size Bi2Se3 films by an order of magnitude, while maintaining the regularly reported doping problems of topological insulators. 

Chiral semiconductors have been recently suggested as the basic building blocks for the design of chiral optoelectronic and electronic devices for chiral emission and spintronics. Herein, we report that through the formation of a chiral/achiral heterostructure, one can develop a chiral system that integrates the merits of both chiral and achiral components for developing a demanded chiral emitter. In the R-(+)-(or S-(−)-)1-(1-naphthyl)-ethylammonium lead bromide/CsPbBr3 heterostructure, we show that the photoluminescence of CsPbBr3 carries a degree of circular polarization of around 1% at room temperature. It is explained that such chiral emission is enabled through the chiral self-trapped exitonic absorption of R-(+)- (or S-(−)-)1-(1-naphthyl)-ethylammonium lead bromide. This work may provide an alternative way to generate bright circularly polarized light from achiral materials, which has potential applications in spintronics, biosensing, and signal encryption. 

Inversion symmetry breaking could lead to the creation of a Rashba–Dresselhauls magnetic field, which plays the key role in spintronic devices. In this work, we propose and develop a composition gradient engineering approach that breaks inversion symmetry into inorganic halide perovskites with strong spin–orbit coupling. We synthesize epitaxial CsPbBr x Cl (3− x ) with Br/Cl composition gradient by a two-step chemical vapor deposition approach. Through optoelectronic measurements, we show the presence of circular photogalvanic effects (CPGEs), evidencing a Rashba-like spin polarized band structure. By spatially resolved photoluminescence spectra, we find that the observed CPGE is likely a cumulative result of inversion symmetry-broken interfaces featured by abrupt and stepwise composition gradient between the pristine and separated daughter phases. Our work suggests an avenue in engineering the spintronic property of halide perovskites for information processing.