相关论文: AFM and Raman studies of topological insulator mat…
In the recently discovered class of materials known as topological insulators, the presence of strong spin-orbit coupling causes certain topological invariants in the bulk to differ from their values in vacuum. The sudden change of…
Raman scattering [K. M. F. Shahil et al., Appl. Phys. Lett. 96, 153103 (2010), V. Gnezdilov et al., Phys. Rev. B 84, 195118 (2011) and H. H. Kung et al., Phys. Rev. B 95, 245406 (2017)], inelastic helium scattering [X. Zhu et al., Phys.…
Bismuth telluride - Bi(2)Te(3)- and related compounds have recently attracted strong interest owing to the discovery of the topological insulator properties in many members of this family of materials. The few-quintuple films of these…
We report crystal growth and Raman spectroscopy characterization of pure and mixed bulk topological insulators. The series comprises of both binary and ternary tetradymite topological insulators. We analyzed in detail the Raman peaks of…
We report the isotropic plasma atomic layer etching (ALE) of aluminum nitride using sequential exposures of SF$_6$ plasma and trimethylaluminum (Al(CH$_3$)$_3$, TMA). ALE was observed at temperatures greater than 200 $^\circ$C, with a…
Ultra-thin topological insulator nanostructures, in which coupling between top and bottom surface states takes place, are of great intellectual and practical importance. Due to the weak Van der Waals interaction between adjacent quintuple…
The main goal of this research was to determine the key reagents during the highly Si3N4/SiO2 selective etching. The experiments were conducted, where both Si3N4 and SiO2 samples were etched by NF3/O2 and NF3/O2/N2/H2 plasmas. The sources…
We report on a >100-fold enhancement of Raman responses from Bi2Se3 thin films if laser photon energy switches from 2.33 eV (532 nm) to 1.58 eV (785 nm), which is due to direct optical coupling to Dirac surface states (SS) at the resonance…
There have been continuous efforts to seek for novel functional two-dimensional semiconductors with high performance for future applications in nanoelectronics and optoelectronics. In this work, we introduce a successful experimental…
We study a crystallographic etching process of graphene nanostructures where zigzag edges can be prepared selectively. The process involves heating exfoliated single-layer graphene samples with a predefined pattern of antidot arrays in an…
Focused ion beam milling allows manipulation of the shape and size of nanostructures to create geometries potentially useful for opto-electronics, thermoelectrics, and quantum computing. We focus on using the ion beam to control the…
Single-layer graphene structures and devices are commonly defined using reactive ion etching and plasma etching with O2 or Ar as the gaseous etchants. Although optical microscopy and Raman spectroscopy are widely used to determine the…
Bi2Se3 is a prototypical topological insulator which has a small band gap (~0.3 eV) and topologically protected conducting surface states. This material exhibits quite strong thermoelectric effects. Here we show in a mechanically exfoliated…
Plasmons are the quantized collective oscillations of electrons in metals and doped semiconductors. The plasmons of ordinary, massive electrons are since a long time basic ingredients of research in plasmonics and in optical metamaterials.…
The deposition of dielectric materials on graphene is one of the bottlenecks for unlocking the potential of graphene in electronic applications. In this paper we demonstrate the plasma enhanced atomic layer deposition of 10 nm thin high…
On-chip photonic devices based on SiO$_2$ are of interest for applications such as microresonator gyroscopes and microwave sources. Although SiO$_2$ microdisk resonators have achieved quality factors exceeding one billion, this value…
Cr2Ge2Te6 has been of interest for decades, as it is one of only a few ferromagnetic insulators. Recently, this material has been revisited due to its potential as a substrate for Bi2Te3, a topological insulator. This enables the…
The use of simple, fast and economic experimental tools to characterize low-dimensional materials is an important step in the process of democratizing the use of such materials in laboratories around the world. Raman spectroscopy has arisen…
Lithium niobate (LiNbO$_3$, LN) is a ferroelectric crystal of interest for integrated photonics owing to its large second-order optical nonlinearity and the ability to impart periodic poling via an external electric field. However, on-chip…
We investigate the quality of hydrogen plasma defined graphene edges by Raman spectroscopy, atomic resolution AFM and low temperature electronic transport measurements. The exposure of graphite samples to a remote hydrogen plasma leads to…