Related papers: Photocurrents in Bi2Se3: bulk versus surface, and …
Directional photocurrents in two-dimensional materials arise from broken crystal symmetry, offering pathways to high-speed, bias-free photodetection beyond conventional devices. Tungsten ditelluride (WTe$_2$), a type-II Weyl semimetal,…
Bi2Se3 is a topological insulator with metallic surface states residing in a large bulk bandgap. It is believed that Bi2Se3 gets additional n-type doping after exposure to atmosphere, thereby reducing the relative contribution of surface…
Electrical field control of the carrier density of topological insulators (TI) has greatly expanded the possible practical use of these materials. However, the combination of low temperature local probe studies and a gate tunable TI device…
We consider in our work high quality single crystal thin films of Bi2Se3, grown by molecular beam epitaxy, both with and without Pb doping. Our ARPES data demonstrate topological surface states with a Fermi level lying inside the bulk band…
Terahertz (THz) technologies have been of interest for many years due to the variety of applications including gas sensing, nonionizing imaging of biological systems, security and defense, etc. To date, scientists have used different…
Excitation of a topological insulator by a high-frequency electric field of a laser radiation leads to a dc electric current in the helical edge channel whose direction and magnitude are sensitive to the radiation polarization and depend on…
The development of nanoscale solid-state devices exploiting the promising topological surface states of topological insulator materials requires careful device engineering and improved materials quality. For instance, the introduction of a…
Topological insulators provide a new platform for spintronics due to the spin texture of the surface states that are topologically robust against elastic backscattering. Here, we report on an investigation of the measured voltage obtained…
The bulk photovoltaic effect (BPVE) offers a promising avenue to surpass the efficiency limitations of current solar cell technology. However, disentangling intrinsic and extrinsic contributions to photocurrent remains a significant…
We report the observation of second harmonic generation with high conversion efficiency $\sim 0.005\%$ in the terahertz regime from thin films of the topological insulator Bi$_2$Se$_3$ that exhibit the linear photogalvanic effect, measured…
We introduce a dinstint approach to engineer a topologically protected surface state of a topological insulator. By covering the surface of a topological insulator, Bi2Te2Se, with a Bi monolayer film, the original surface state is…
Topological insulators are a new phase of matter that exhibits exotic surface electronic properties. Determining the spin texture of this class of material is of paramount importance for both fundamental understanding of its topological…
The light absorption due to the transitions between the edge and two-dimensional (2D) states of a 2D topological insulator (TI) is considered in the Volkov-Pankratov model. It is shown that the transitions are allowed only for the in-plane…
We report the exotic photoluminescence (PL) behaviour of 3D topological insulator Bi2Te3 single crystals grown by customized self-flux method and mechanically exfoliated few layers (18 plus minus 2 nm)/thin flakes obtained by standard…
We explore the application of excitation correlation spectroscopy to detect nonlinear photophysical dynamics in two distinct semiconductor classes through time-integrated photoluminescence and photocurrent measurements. In this experiment,…
The optical conductivity and the spectral weight of four topological insulators with increasing chemical compensation (Bi2Se3, Bi2-xCaxSe3, Bi2Se2Te, Bi2Te2Se) have been measured from 5 to 300 K and from sub-THz to visible frequencies. The…
Although the absorption of light in a bulk homogeneous semiconductor produces photocarriers with non-zero momentum, it generally does not produce a current in the absence of an applied electric field because equal amounts of carriers with…
Two-dimensional ferroelectrics have recently emerged as a promising avenue for next-generation optoelectronic and photovoltaic devices. Due to the intrinsic absence of inversion symmetry, 2D ferroelectrics exhibit bulk photovoltaic effect…
We predict that unpolarized charge current injected into a ballistic thin film of prototypical topological insulator (TI) Bi$_2$Se$_3$ will generate a {\it noncollinear spin texture} $\mathbf{S}(\mathbf{r})$ on its surface. Furthermore, the…
Complex electron-microscopic, energy-dispersed and wide-temperature optical absorption and photoluminescence (PL) investigations are carried out into Bridgeman-grown layered In2Se3 crystals. It is shown that In2Se3 crystals as a whole have…