SearcharxivSearch

arXiv subjects

Shengqiang Huang

Publications and source records attributed to Shengqiang Huang.

6 recordsLinked to original sources

A Survey on Cross-Architectural IoT Malware Threat Hunting

In recent years, the increase in non-Windows malware threats had turned the focus of the cybersecurity community. Research works on hunting Windows PE-based malwares are maturing, whereas the developments on Linux malware threat hunting are relatively scarce. With the advent of the Internet of Things (IoT) era, smart devices that are getting integrated into human life have become a hackers highway for their malicious activities. The IoT devices employ various Unix-based architectures that follow ELF (Executable and Linkable Format) as their standard binary file specification. This study aims at providing a comprehensive survey on the latest developments in cross-architectural IoT malware detection and classification approaches. Aided by a modern taxonomy, we discuss the feature representations, feature extraction techniques, and machine learning models employed in the surveyed works. We further provide more insights on the practical challenges involved in cross-architectural IoT malware threat hunting and discuss various avenues to instill potential future research.

cs.CR

Topologically Protected Helical States in Minimally Twisted Bilayer Graphene

In minimally twisted bilayer graphene, a moir{é} pattern consisting of AB and BA stacking regions separated by domain walls forms. These domain walls are predicted to support counterpropogating topologically protected helical (TPH) edge states when the AB and BA regions are gapped. We fabricate designer moir{é} crystals with wavelengths longer than 50 nm and demonstrate the emergence of TPH states on the domain wall network by scanning tunneling spectroscopy measurements. We observe a double-line profile of the TPH states on the domain walls, only occurring when the AB and BA regions are gapped. Our results demonstrate a practical and flexible method for TPH state network construction.

cond-mat.mes-hall

Evolution of the electronic band structure of twisted bilayer graphene upon doping

The electronic band structure of twisted bilayer graphene develops van Hove singularities whose energy depends on the twist angle between the two layers. Using Raman spectroscopy, we monitor the evolution of the electronic band structure upon doping using the G peak area which is enhanced when the laser photon energy is resonant with the energy separation of the van Hove singularities. Upon charge doping, the Raman G peak area initially increases for twist angles larger than a critical angle and decreases for smaller angles. To explain this behavior with twist angle, the energy of separation of the van Hove singularities must decrease with increasing charge density demonstrating the ability to modify the electronic and optical properties of twisted bilayer graphene with doping.

cond-mat.mtrl-sci

Tunable Moiré Bands and Strong Correlations in Small-Twist-Angle Bilayer Graphene

According to electronic structure theory, bilayer graphene is expected to have anomalous electronic properties when it has long-period moiré patterns produced by small misalignments between its individual layer honeycomb lattices. We have realized bilayer graphene moiré crystals with accurately controlled twist angles smaller than 1 degree and studied their properties using scanning probe microscopy and electron transport. We observe conductivity minima at charge neutrality, satellite gaps that appear at anomalous carrier densities for twist angles smaller than 1 degree, and tunneling densities-of-states that are strongly dependent on carrier density. These features are robust up to large transverse electric fields. In perpendicular magnetic fields, we observe the emergence of a Hofstadter butterfly in the energy spectrum, with four-fold degenerate Landau levels, and broken symmetry quantum Hall states at filling factors 1, 2, 3. These observations demonstrate that at small twist angles, the electronic properties of bilayer graphene moiré crystals are strongly altered by electron-electron interactions.

cond-mat.mes-hall

Intrinsic disorder in graphene on transition metal dichalcogenide heterostructures

The electronic properties of two-dimensional materials such as graphene are extremely sensitive to their environment, especially the underlying substrate. Planar van der Waals bonded substrates such as hexagonal boron nitride (hBN) have been shown to greatly improve the electrical performance of graphene devices by reducing topographic variations and charge fluctuations compared to amorphous insulating substrates}. Semiconducting transition metal dichalchogenides (TMDs) are another family of van der Waals bonded materials that have recently received interest as alternative substrates to hBN for graphene as well as for components in novel graphene-based device heterostructures. Additionally, their semiconducting nature permits dynamic gate voltage control over the interaction strength with graphene. Through local scanning probe measurements we find that crystalline defects intrinsic to TMDs induce scattering in graphene which results in significant degradation of the heterostructure quality, particularly compared to similar graphene on hBN devices.

cond-mat.mtrl-sci

Gate dependent Raman spectroscopy of graphene on hexagonal boron nitride

Raman spectroscopy, a fast and nondestructive imaging method, can be used to monitor the doping level in graphene devices. We fabricated chemical vapor deposition (CVD) grown graphene on atomically flat hexagonal boron nitride (hBN) flakes and SiO$_2$ substrates. We compared their Raman response as a function of charge carrier density using an ion gel as a top gate. The G peak position, 2D peak position, 2D peak width and the ratio of the 2D peak area to the G peak area show a dependence on carrier density that differs for hBN compared to SiO$_2$. Histograms of two-dimensional mapping are used to compare the fluctuations in the Raman peak properties between the two substrates. The hBN substrate has been found to produce fewer fluctuations at the same charge density owing to its atomically flat surface and reduced charged impurities.

cond-mat.mtrl-sci