Recent Advances in Silicon Photodetectors Based on the Internal Photoemission Effect

Silicon technologies provide an excellent platform in order to realize microsystems where photonic and microelectronic functionalities are monolithically integrated on the same substrate. In recent years, a lot of passive and active silicon photonic devices have been optimized to work at telecom wavelengths where, unfortunately, silicon has a neglectable optical absorption due to its bandgap of 1.12 eV. Although silicon cannot detect wavelengths above 1.1 μm, in recent years, tremendous advances have been made in order to make it suitable for operation in the near-infrared spectrum. One of the approaches is to take advantage of the internal photoemission effect through a Schottky junction where a metal absorbs the incoming radiation and emits hot carriers into silicon making sub-bandgap detection possible. The present chapter describes the more recent advances in the field of the silicon photodetectors based on the internal photoemission effect showing as devices based on new emerging materials and complex nanostructure are leading this family of device to compare favorably with the well-established technologies commonly used for telecom wavelengths based on germanium and III–V semiconductors

State-of-the-art all-silicon sub-bandgap photodetectors at telecom and datacom wavelengths

Silicon-based technologies provide an ideal platform for the monolithic integration of photonics and microelectronics. In this context, a variety of passive and active silicon photonic devices have been developed to operate at telecom and datacom wavelengths, at which silicon has minimal optical absorption - due to its bandgap of 1.12 eV. Although in principle this transparency window limits the use of silicon for optical detection at wavelengths above 1.1 μm, in recent years tremendous advances have been made in the field of all-silicon sub-bandgap photodetectors at telecom and datacom wavelengths. By taking advantage of emerging materials and novel structures, these devices are becoming competitive with the more well-established technologies, and are opening new and intriguing perspectives. In this paper, a review of the state-of-the-art is presented. Devices based on defect-mediated absorption, two-photon absorption and the internal photoemission effect are reported, their working principles are elucidated and their performance discussed and compared

Risk, Human Behavior, and Theories inOrganizational Studies

The present paper regards risk, threats and organizational issues that are associated with human behavior;e.Business is no exception[2]. Organizational actors in e.Businessorganizations make security decisions with a wide variety of meanings[3]: information systems interactions, access to physical premises, behavior within the workplace, utilization of tools and work instruments, are just a few examples of the realm of security decisions that are made within all organizations, and e.Business organizations in particular. The way in which the risk is perceived greatly influences any decision. The aim of the present paper is to conjugate general risk theories in terms of human behavior and system security (as opposed to system risk) in order to identify a common baseline ofrisk and behavior, that will lead eventually lead to a structured framework that will contribute to the discipline of organizational studies

Asymmetric MSM sub-bandgap all-silicon photodetector with low dark current

Design, fabrication, and characterization of an asymmetric metal-semiconductor-metal photodetector, based on internal photoemission effect and integrated into a silicon-on-insulator waveguide, are reported. For this photodetector, a responsivity of 4.5 mA/W has been measured at 1550 nm, making it suitable for power monitoring applications. Because the absorbing metal is deposited strictly around the vertical output facet of the waveguide, a very small contact area of about 3 µm2 is obtained and a transit-time-limited bandwidth of about 1 GHz is demonstrated. Taking advantage of this small area and electrode asymmetry, a significant reduction in the dark current (2.2 nA at -21 V) is achieved. Interestingly, applying reverse voltage, the photodetector is able to tune its cut-off wavelength, extending its range of application into the MID infrared regime

Critically coupled silicon Fabry-Perot photodetectors based on the internal photoemission effect at 1550 nm

In this paper, design, fabrication and characterization of an all-silicon photodetector (PD) at 1550 nm, have been reported. Our device is a surface-illuminated PD constituted by a Fabry-Perot microcavity incorporating a Cu/p-Si Schottky diode. Its absorption mechanism, based on the internal photoemission effect (IPE), has been enhanced by critical coupling condition. Our experimental findings prove a peak responsivity of 0.063 mA/W, which is the highest value obtained in a surface-illuminated IPE-based Si PD around 1550 nm. Finally, device capacitance measurements have been carried out demonstrating a capacitance < 5 pF which has the potential for GHz operation subject to a reduction of the series resistance of the ohmic contact

Near-Infrared Schottky Silicon Photodetectors Based on Two Dimensional Materials

Since its discovery in 2004, graphene has attracted the interest of the scientific community due to its excellent properties of high carrier mobility, flexibility, strong light-matter interaction and broadband absorption. Despite of its weak light optical absorption and zero band gap, graphene has demonstrated impressive results as active material for optoelectronic devices. This success pushed towards the investigation of new two-dimensional (2D) materials to be employed in a next generation of optoelectronic devices with particular reference to the photodetectors. Indeed, most of 2D materials can be transferred on many substrates, including silicon, opening the path to the development of Schottky junctions to be used for the infrared detection. Although Schottky near-infrared silicon photodetectors based on metals are not a new concept in literature the employment of two-dimensional materials instead of metals is relatively new and it is leading to silicon-based photodetectors with unprecedented performance in the infrared regime. This chapter aims, first to elucidate the physical effect and the working principles of these devices, then to describe the main structures reported in literature, finally to discuss the most significant results obtained in recent years

Performance Management and Innovative Human Resource Training through Flexible Production Systems aimed at Enhancing the Competitiveness of SMEs

In the current knowledge economy companies need to develop competitive advantages based on an adequate and intensive use of innovation processes and ICT that are becoming essential elements of business success in today’s European market. The purpose of this article is to introduce and discuss the benefits of on-line training on automation and innovation fields and try to explain their organizational impact on small and medium-sized enterprises (SME). Besides, it tries to understand what are the main barriers for SMEs with respect to the realisation of their innovative potential and their capacity to improve internal processes by ICT adoption and organizational change. They are becoming particularly important for achieving greater productivity, lower operational costs, and higher revenues (usually characterized by reduced access to external finance, unavailability of wider distribution channels, low internationalization, etc.). The goal of the article is also to synthetize the experience done and the benefits of e-learning and of a specific professional environment in the training process. The described project provides training contents to enhance participants’ background and some innovative simulations to improve effectively the specialised knowledge of employees on industrial automation systems

A New Approach to Enhance the Strategic Impact of Digital Education in Universities and to Foster the Development of a High Performing Common EU Smart Education Ecosystem

In response to the negative COVID-19 impacts, it is urgent to support digital transformation plans at all levels of educational online activities. Fundamental it is also to support new inclusive digital pedagogical methods and skills for a resilient free adoption of digital tools for academic teachers (digital integrated learning, advanced multimedia, but also hybrid and interactive new methodologies, 3D, VR, holographic tools, etc.) and allow effective use for students, including participants with fewer opportunities: physically impaired (deaf, blind, paralytic), cognitive impaired and low-income students. This to create the condition of a more EU integrated strategy to consent the proposal for a Council Recommendation on the enabling factors for successful digital education by 2022–2025. We are following and improving the recommendations of OECD and UN, of EU Future Government 2030+, of EU’s strategy for e-Skills in the 21st Century, of KES international network and of FOME - Future of Management Education international scientific alliance. Also, some new EU Directives will imply a real digital revolution in educational processes and learning skills. So digital technologies have made this transition possible: surely, there have been a number of e-learning platforms for some years now, but their role has only in the last months gained massive relevance concurrently with the pandemic global situation. Only a few EU Universities are already ready for good quality distance learning, with tools for course management, including live sessions, interactive teaching and collaborative activities. Most EU Universities had to cope with the emergency situation that called for a quick organizational and cultural rearrangement and a change of learning strategies, which perhaps represented the most difficult step for teachers and students. Digital technologies are becoming very relevant at the EU level for teachers and students. However, the current limitations on the movement of people and teaching hours may restrict this type of delivery. For this reason, the described EDU-GATE initiative is providing a detailed European multi-sectoral analysis indicating the comparison of current situations of teaching digitalization (As-Is and To-Be analysis), together with a transversal needs’ analysis. Also, a smart innovative curriculum, including the most advanced educational design and delivering techniques, has been created for the improvement of teachers’ skills. Almost 12 innovative multimedia e-modules have been prepared, permitting effective learning activities and to share best practices in the EU

Bioconjugation of a PNA Probe to Zinc Oxide Nanowires for Label-Free Sensing

Zinc oxide nanowires (ZnONWs) are largely used in biosensing applications due to their large specific surface area, photoluminescence emission and electron mobility. In this work, the surfaces of ZnONWs are modified by covalent bioconjugation of a peptidic nucleic acid (PNA) probe whose sequence is properly chosen to recognize a complementary DNA (cDNA) strand corresponding to a tract of the CD5 mRNA, the main prognostic marker of chronic lymphatic leukemia. The interaction between PNA and cDNA is preliminarily investigated in solution by circular dichroism, CD melting, and polyacrylamide gel electrophoresis. After the immobilization of the PNA probe on the ZnONW surface, we demonstrate the ability of the PNA-functionalized ZnONW platform to detect cDNA in the μM range of concentration by electrical, label-free measurements. The specificity of the sensor is also verified against a non-complementary DNA sequence. These preliminary results highlight the potential application of PNA-bioconjugated ZnONWs to label-free biosensing of tumor markers