Ultra-low-cost broad-band near-infrared silicon photodetectors based on hot electrons

Cataloged from PDF version of article.Silicon is at the heart of all of the end-user digital devices such as smart phones, laptops, and wearable technologies. It is the holy grail for the largescale production of semiconductor devices since start of the semiconductor era due to its relatively good electrical, mechanical and chemical properties. Silicon’s mediocre optical properties also make it an acceptable material for energy harvesting and ultraviolet photodetection applications. But its relatively large bandgap (1.12 eV ) makes it infrared blind. So Silicon photodetectors fail to detect infrared light using traditional techniques. Hence, an all-Silicon solution is of interest for low-cost civil applications like telecommunication and imaging. Silicon based Schottky junction is a promising candidate for infrared photodetection. Internal photoemission is the main mechanism of photodetection in the Schottky junctions. Incident photons elevate the kinetic energy of the electrons in the metal so that the energetic electrons can jump over the Schottky barrier or tunnel through it. Carefully designed metal contact of the Schottky junction can, at the same time, give rise to hot electron generation through plasmon resonances. Here we introduce ultra-low-cost broad-band near-infrared Silicon photodetectors with a study over types of metal and nanostructures and fabrication techniques. The devices exhibit photoresponsivity as high as 2 mA/W and 600 µA/W at 1300 nm and 1550 nm wavelengths, and can see beyond 2000 nm wavelengths. Their dark current density is as low as 50 pA/µm2 . Simplicity and scalability of fabrication in this type of structures make them the most cost effective infrared detectors due to lack of expensive fabrication steps such as sub-micron lithography and high temperature epitaxial growth techniques.Nazirzadeh, Mohammad AminM.S

Ultra-low-cost near-infrared photodetectors on silicon

We demonstrate Silicon-only near-infrared (NIR) photodetectors (sensitive up to 2000 nm) that meet large-scale ultralow-cost fabrication requirements. For the detection of infrared photons, we use metal nanoislands that form Schottky contact with Silicon. NIR photons excite plasmon resonances at metal nanoislands and plasmons decay into highly energetic charge carriers (hot electrons). These hot electrons get injected into Silicon (internal photoemission), resulting in photocurrent. Several groups have studied plasmonic nanoantennas using high resolution lithography techniques. In this work, we make use of randomly formed nanoislands for broad-band photoresponse at NIR wavelengths. We observe photoresponse up to 2000 nm wavelength with low dark current density about 50 pA/μm2. The devices exhibit photoresponsivity values as high as 2 mA/W and 600 μA/W at 1.3 μm and 1.55 μm wavelengths, respectively. Thin metal layer was deposited on low-doped n-type Silicon wafer. Rapid thermal annealing results in surface reconstruction of the metal layer into nanoislands. Annealing conditions control the average size of the nanoislands and photoresponse of the devices. An Al-doped Zinc Oxide (AZO) layer was deposited on the nanoislands using thermal atomic layer deposition (ALD) technique to acts as a transparent conductive oxide (TCO) and patterned using photolithography. AZO film creates electrical connection between the nanoislands and also makes a heterojunction to Silicon. Simple and scalable fabrication on Si substrates without the need for any sub-micron lithography or high temperature epitaxy process make these devices good candidates for ultra-low-cost broad-band NIR imaging and spectroscopy applications. © 2015 SPIE

Growth of ∼3-nm ZnO nano-islands using Atomic Layer Deposition

In this work, the deposition of 3-nm dispersed Zinc-Oxide (ZnO) nanislands by thermal Atomic Layer Deposition (ALD) is demonstrated. The physical and electronic properties of the islands are studied using Atomic Force Microscopy, UV-Vis-NIR spectroscopy, and X-ray Photoelectron Spectroscopy. The results show that there is quantum confinement in 1D in the nanoislands which is manifested by the increase of the bandgap and the reduction of the electron affinity of the ZnO islands. The results are promising for the fabrication of future electronic and optoelectronic devices by single ALD step. © 2016 IEEE

∼3-nm ZnO nanoislands deposition and application in charge trapping memory grown by single ALD step

Low-dimensional semiconductor nanostructures are of great interest in high performance electronic and photonic devices. ZnO is considered to be a multifunctional material due to its unique properties with potential in various applications. In this work, 3-nm ZnO nanoislands are deposited by Atomic Layer Deposition (ALD) and the electronic properties are characterized by UV-Vis-NIR Spectrophotometer and X-ray Photoelectron Spectroscopy. The results show that the nanostructures show quantum confinement effects in 1D. Moreover, Metal-Oxide-Semiconductor Capacitor (MOSCAP) charge trapping memory devices with ZnO nanoislands charge storage layer are fabricated by a single ALD step and their performances are analyzed. The devices showed a large memory window at low operating voltages with excellent retention and endurance characteristics due to the additional oxygen vacancies in the nanoislands and the deep barrier for the trapped holes due to the reduction in ZnO electron affinity. The results show that the ZnO nanoislands are promising in future low power memory applications. © The Author(s) 2016

Zihinsel engelli çocuklar için temel yaşam becerileri öğretmek amaçlı bedensel hareket oyunları geliştirilmesi.

Students with mental disabilities often have trouble generalizing concepts and skills from one setting to another. An alternative way to teach generalization is to teach students solve problems pertinent to their daily lives and to reinforce behaviors that would occur in the natural environment. In this thesis, we propose a system to augment the environment for mentally disabled students in order to easily cope with life skills by game and fun. The games were developed for motion sensing input devices by following spiral iterative methodology. In the start, game concepts were approved by a special education subject matter expert and then prototypes were developed and tested. In the next step, feedback used to improve prototypes. This process continued until a satisfactory bodily movement game for special education children is developed. In addition to this, we also tested and improved usability approach for bodily movement games for special education children. The results show positive effects of the developed game in special education.M.S. - Master of Scienc

Developing A Gesture-Based Game For Mentally Disabled Peopleto Teach Basic Life Skills

It is understood that, for mentally disabled people, it is hard to generalize skills and concepts from one setting to another. One approach to teach generalization is solving the problems related to their daily lives, which helps them to reinforce some of their behaviors that would occur in the natural environment. The aim of this study is to develop a gesture based game to teach basic life skills to mentally disabled kids by a motion sensing device. To this end, a vacuum cleaning digital video game was designed by using the Unity3D game engine, and Microsoft Kinect, based on spiral development methodology. Tests were conducted in two special education schools with the help of a special education expert. The game prototypes were tested on various spectrum of mentally disabled children, and a final game was designed after several iterations. Results were extracted by observation of the participant's performances. Results have shown that this system positively helps children's basic life skills learnin

Random sized plasmonic nanoantennas on Silicon for low-cost broad-band-near-infrared photodetection

Cataloged from PDF version of article.In this work, we propose Silicon based broad-band near infrared Schottky barrier photodetectors. The devices operate beyond 1200 nm wavelength and exhibit photoresponsivity values as high as 3.5 mA/W with a low dark current density of about 50 pA/mu m(2). We make use of Au nanoislands on Silicon surface formed by rapid thermal annealing of a thin Au layer. Surface plasmons are excited on Au nanoislands and this field localization results in efficient absorption of sub-bandgap photons. Absorbed photons excite the electrons of the metal to higher energy levels (hot electron generation) and the collection of these hot electrons to the semiconductor results in photocurrent (internal photoemission). Simple and scalable fabrication makes these devices suitable for ultra-low-cost NIR detection applications

The investigation of photons energy distribution changing in ignition condition of equimolar deuterium- tritium fuel

At the beginning of thermonuclear ignition in fusion plasma, the bremsstrahlung radiation is dominant phenomenon, the photons distribution function is Planckian and plasma is considered as optically thick one. But at a certain energy, the bremsstrahlung radiation and Compton scattering losses rates become equal and plasma makes a transition from optically thick to optically thin and photons distribution switches from Planckian to a Bose-Einstein one. Dominating the Compton scattering and conservation of photon number density in this event, cause to increase the photons temperature and to decrease the negative role of Compton scattering in electrons balance equation. In this paper the photons distribution change effect in calculating of critical burn-up parameter by using of a Fortran programming code is investigated and the results are compared with a typical case where the photons have Planckian distribution throughout the ignition