Spot The Odd One Out: Regularized Complete Cycle Consistent Anomaly Detector GAN

This study presents an adversarial method for anomaly detection in real-world applications, leveraging the power of generative adversarial neural networks (GANs) through cycle consistency in reconstruction error. Previous methods suffer from the high variance between class-wise accuracy which leads to not being applicable for all types of anomalies. The proposed method named RCALAD tries to solve this problem by introducing a novel discriminator to the structure, which results in a more efficient training process. Additionally, RCALAD employs a supplementary distribution in the input space to steer reconstructions toward the normal data distribution, effectively separating anomalous samples from their reconstructions and facilitating more accurate anomaly detection. To further enhance the performance of the model, two novel anomaly scores are introduced. The proposed model has been thoroughly evaluated through extensive experiments on six various datasets, yielding results that demonstrate its superiority over existing state-of-the-art models. The code is readily available to the research community at https://github.com/zahraDehghanian97/RCALAD.Comment: under revision of Applied Soft Computing Journa

Graphene Schottky diodes: an experimental review of the rectifying graphene/semiconductor heterojunction

In the past decade graphene has been one of the most studied material for several unique and excellent properties. Due to its two dimensional nature, physical and chemical properties and ease of manipulation, graphene offers the possibility of integration with the exiting semiconductor technology for next-generation electronic and sensing devices. In this context, the understanding of the graphene/semiconductor interface is of great importance since it can constitute a versatile standalone device as well as the building-block of more advanced electronic systems. Since graphene was brought to the attention of the scientific community in 2004, the device research has been focused on the more complex graphene transistors, while the graphene/semiconductor junction, despite its importance, has started to be the subject of systematic investigation only recently. As a result, a thorough understanding of the physics and the potentialities of this device is still missing. The studies of the past few years have demonstrated that graphene can form junctions with 3D or 2D semiconducting materials which have rectifying characteristics and behave as excellent Schottky diodes. The main novelty of these devices is the tunable Schottky barrier height, a feature which makes the graphene/semiconductor junction a great platform for the study of interface transport mechanisms as well as for applications in photo-detection, high-speed communications, solar cells, chemical and biological sensing, etc. In this paper, we review the state-of-the art of the research on graphene/semiconductor junctions, the attempts towards a modeling and the most promising applications.Comment: 85 pages. Review articl

Feasibility of Room-Temperature GHz-THz Direct Detection in Graphene Through Hot-Carrier Effect

Recent theories suggest that the photo thermoelectric effect dominates the photo response in graphene. Hot-carrier generation arising from carrier multiplication in graphene under the incident light is introduced as the main cause of this effect. Here, we investigate the possibility of GHz-THz direct detection in a graphene-based device through Hot-carrier effect. The proposed structure is a Schottky junction between graphene and Si. We have measured the optical properties of the junction under 86 GHz and 0.102 THz radiations at room temperature. We have repeated the experiments at cryogenic temperatures down to 150 K. The minimum responsivity of the junction is measured as 2x10(4) V/W under 0.102 THz radiations at room temperature. This value increases five-fold at the cryogenic temperatures. We discuss the physics behind room temperature operation of the device based on the photo thermoelectric effect and the hot-carrier generation in graphene under the illuminations. Room temperature and direct detection of GHz and THz radiation in the graphene-Si junction can be practical evidence of hot-carrier generation in graphene under the incident illuminations

Graphene-Si Schottky IR Detector

This paper reports on photodetection properties of graphene-Si schottky junction by measuring current-voltage characteristics under 1.55\ub5m excitation laser. The measurements have been done on a junction fabricated by depositing mechanically exfoliated natural graphite on top of the pre-patterned silicon substrate. The electrical Schottky barrier height is estimated to be (0.44-0.47) eV with a minimum responsivity of 2.8mA/W corresponding to an internal quantum efficiency of 10% which is almost an order of magnitude larger than regular Schottky junctions. A possible explanation for the large quantum efficiency related to the 2-D nature of graphene is discussed. Large quantum efficiency, room temperature IR detection, ease of fabrication along with compatibility with Si devices can open a doorway for novel graphene-based photodetectors