Photodetectors

Experimental performance evaluation of heat pump-based steam supply system T Kaida, I Sakuraba, K Hashimoto et al. -Fluid-Structure interaction analysis and performance evaluation of a membrane blade M. Saeedi, R. Wüchner and K.-U. Bletzinger -Optimization and performance evaluation for nutrient removal from palm oil mill effluent wastewater using microalgae Raheek I Ibrahim, Z H Wong and A W Mohammad -This content was downloaded from IP address 168.151.1.23 on 24/09

The first sub-100nm technology that allows the monolithic integration of optical modulators and germanium photodetectors as features into a current 90nm base highperformance logic technology node is demonstrated. The resulting 90nm CMOS-integrated Nano-Photonics technology node is optimized for analog functionality to yield powerefficient single-die multichannel wavelength-mulitplexed 25Gbps transceivers.

Using scintillation crystal sheets instead of discrete crystal arrays in high-resolution PET has the immediate advantage of reduced complexity as well as a potential for increased sensitivity. In order to evaluate the positioning capability of a position sensitive avalanche photodioide (PSAPD) using a sheet Lutetium Oxyorthosilicate (LSO) crystal scintillator, we studied the dependence of detected event position versus the known source position. In particular, we studied positioning in a continuous 8 mm 8 mm LSO sheet coupled to a PSAPD with an 8 mm 8 mm active area experimentally, studied optical transport in the sheet crystal with Monte Carlo simulation, and used two positioning methods to evaluate PSAPD pincushioning effects. Both collimated 57 Co 122 keV and coincidence-triggered 22 Na 511 keV sources were used in the experiments performed. We analyze the energy resolution, sensitivity, photopeak position and spatial resolution as a function of source position. An average point spread function (PSF) resolution of 2.86 and 1.12 mm FWHM for 57 Co and 22 Na respectively was observed. Within 1.2 mm from the edge of the LSO sheet, the average photopeak position change was 5%. Simulations using annihilation photon interactions from GATE and scintillation photon transport from DETECT2000, as well as utilizing a pincushion-reduction posioning algorithm, have confirmed that the positioning and energy response observed experimently at the edge of the crystal is due to optical transport near those edges.

Interband cascade (IC) infrared (IR) photodetectors (ICIPs) are a new type of detector that combines features of conventional interband photodiodes with the discrete nature of quantum-well IR photodetectors (QWIPs) and IC lasers. The operation of ICIPs takes advantage of fast intersubband relaxation and interband tunneling for carrier transport, and relatively slow interband transitions (long lifetime) for photon generation. As such, ICIPs can be tailored to optimize device performance for specific application requirements. We report our initial efforts in the development of ICIPs. We have observed the photocurrent from an InAs-based IC laser with a cutoff wavelength near 8 μm at 80 K, and significant photocurrent from GaSb-based ICIPs with cutoff wavelengths near 5 μm at 80 K and 7 μm at above room temperature.

We report an ultracompact label-free biosensor that uses a vertical-cavity surface-emitting laser (VCSEL)-based measurement system for the characterization of biomolecular interactions. It consists of a VCSEL, a plastic guided-mode resonant filter, and two p-in detectors. The system has demonstrated very high sensitivity to molecules on top of the sensor.

We report on a systematic investigation of temperature dependent current-voltage (I-V) characteristics of Pd/ZnO Schottky barrier diodes in the 30-300 K temperature range. The ideality factor was observed to decrease with increase in temperature, whilst the barrier height increases with increase in temperature. The observed trend has been attributed to barrier inhomogeneities, which results in a distribution of barrier heights at the interface. Using the dependence of saturation current values on temperature, we have calculated the Richardson constant (A *) which was investigated in the two distinct temperature regions: 140-200 K and 210-300 K and values of and A cm-2 K-2 were obtained, respectively. A mean barrier height of 0.97 eV was obtained in the 140-300 K temperature range. Applying the barrier height inhomogeneities correction, the value of A * was obtained from the modified Richardson plots as 39.43 and 39.03 A cm-2 K-2 in the 140-200 K and 210-300 K temperature range. The modified Richardson constant (A **) has proved to be strongly affected by barrier inhomogeneities and dependent on contact quality.

Goniometric time-domain spectroscopy (GTDS), employing an ultrashort electromagnetic (EM) pulse technique, has been developed for measuring the dielectric constant of thin films in a broad band of gigahertz to terahertz. An ultrafast optoelectronic system, including an emitter and a detector unit, is constructed with a -2 goniometer. A silicon wafer was analyzed as the reference substrate material. A sharp phase-shift of the reflected EM wave was observed at the Brewster angle of 73.5 for a bare silicon wafer. The phase shift for a film on the Si substrate is relatively smooth due to its two surfaces' providing a complex reflectance. The dielectric constant of the film on Si, related with angular dependency of the phase shift, can be extracted by means of fitting the curve or measuring slope of the curve near the Brewster angle. The measured dielectric constants of FLARE, TiO x , and PZT film are reported.

This paper presents an implementation of a test system for advanced calibration and performance analysis of flickermeters. Tests include not only the complete set of test points reported in IEC Standard 61000-4-15, but also an array of different voltage fluctuations-related to common power quality issues-that may be encountered in actual use. This is done because it can be shown that different flickermeter implementations fully meeting the performance tests defined in IEC Standard can still disagree significantly in some actual measurements. After the description and the performance analysis of the test system, a commercial instrument is tested and its response is presented.

Nanocrystal quantum dot photovoltaics and photodetectors with performance optimized by engineering the nanocrystals size and the optoelectronic properties of the nanocrystal's chemical coating are reported. Due to the large surface-tovolume ratio inherent to nanocrystals, the surface effects of ligands used to chemically coat and passivate nanocrystals play a significant role in device performance. However, the optoelectronic properties of ligands are difficult to ascertain, as the band structure of the ligand-capped nanoparticle system is complex and difficult to model. Using density-of-states measurements, we demonstrate that modeling of electropositive and electronegative substituents and use of the Hammett equation, are useful tools in optimizing nanocrystal detector performance. A new particle, the Janus-II nanoparticles, developed using 'charge-donating' and 'charge-withdrawing' ligands distributed over opposite surfaces of the nanocrystal, is described. The polarizing ligands of the Janus-II nanoparticle form a degeneracy-splitting dipole, which reduces the overlap integral between excitonic states, and thus reduces the probability of carrier recombination, allowing carrier extraction to take place more efficiently. This is shown to allow increased photodetection efficiencies and to allow the capture of multiple exciton events in working photodetectors.

A new technique of color detection based on time-resolved charge collection during transient response measurement using a hydrogenated amorphous silicon detector has been proposed and experimentally demonstrated. The method based on the material intrinsic wavelength-filtering properties is implemented in color sensing by transient response of a detector to a combination of basic colors light and voltage pulse. Resulting transient responses under different illumination and bias voltage conditions confirm considerable accuracy of proposed method. In particular, the best agreement of measured and calculated transient response curves has been obtained by using the spectral response of all three primary colors in calculations. It was observed that the presence of blue light drastically reduces the transient response to a chromatic light illumination. Finally, a voltage pulse influence to the basic colors transient response was found.

A new portable brain imaging device based on continuous-wave functional near-infrared spectrometry (fNIRS) is presented. The source-detector part is composed of a multi-wavelength LED and a silicon photodetector that are directly placed on the scalp of the subject. The dimensions of the proposed device are small, as it has to be mounted on the head of an adult person. Acquired data are transmitted in real-time to a laptop for post processing using Matlab. Timemultiplexed light is used to achieve a higher SNR while keeping the device safe for long-term wearing. Preliminary evaluation on adults gave the expected accuracy and compare well with fNIRS characteristics found in literature, that are collected from bulky equipment. With a noise figure of -47dB and a sampling rate of 23Hz, the presented device is appropriate to isolate hemodynamic variations, which are strongly related to local cerebral activity.

Photodetectors (PDs) are an important active device in optoelectronic integrated circuits (OEICs), and, for shorter haul interconnections where circuit (e.g. transimpedance amplifier (TIA)) noise may be the dominant noise in receivers, metal-semiconductor-metal photodiodes (MSM PDs) are attractive due to their low capacitance per unit area compared to PIN photodetectors and the ease of monolithic integration with field effect transistors (FETs). Inverted-MSM PDs (I-MSM PDs), which are thin film MSM PDs with the fingers on the bottom of the device, have demonstrated higher responsivities compared to conventional MSM PDs while maintaining small capacitance per unit area, low dark current (~nA), and high speed. However, the modeling of MSM PDs and I-MSM PDs for insertion into circuit simulators for integrated PD/TIA modeling has not been reported. In this paper, an accurate highfrequency equivalent circuit-level model of thin film I-MSM PDs is obtained using an on-wafer measurement-based modeling technique. This circuit-level model of MSM PDs can be used for capacitance sensitive preamplifier design for co-optimization with widely used simulators (ADS and HSPICE). The obtained circuit-level model shows good agreement with measured s-parameters.

In the paper recent progress at VIGO/MUT (Military University of Technology) MOCVD Laboratory in the growth of Hg 1−x Cd x Te (HgCdTe) multilayer heterostructures on GaAs/CdTe substrates is presented. The optimum conditions for the growth of single layers and complex multilayer heterostructures have been established. One of the crucial stages of HgCdTe epitaxy is CdTe nucleation on GaAs substrate. Successful composite substrates have been obtained with suitable substrate preparation, liner and susceptor treatment, proper control of background fluxes and appropriate nucleation conditions. The other critical stage is the interdiffused multilayer process (IMP). The growth of device-quality HgCdTe heterostructures requires complete homogenization of CdTe-HgTe pairs preserving at the same time suitable sharpness of composition and doping profiles. This requires for IMP pairs to be very thin and grown in a short time.

Several commercial GaAlAs and InGaAsP injection lasers have been investigated with respect to their photodetection properties. The responsivity of the laser diode detectors is in the 0.15-0.25 AIW range and the dark current ranges from 5 nA to 500 nA at 3-V reverse bias. The high frequency performance of a laser diode detector strongly depends on the laser structure. The bandwidth is determined by the capacitance of the lasers and ranges from 70 MHz to 1.3 GHz. The structure showing the fastest response was the TJS laser due to its low junction capacitance. OF LASER DIODE DETECTORS 1665 * *

Some of these demonstrations were implemented for wearable applications by exploiting the material's exceptional robustness and flexibility. [5,6] However, there remain major obstacles that hinder the industrial adoption of MoS 2 and other 2D TMDC materials. The most challenging obstacle has been finding an industrially compatible method that enables the production of these materials on a mass scale. We have recently demonstrated that electrodeposition is a potentially viable method for solving this challenge. [7,8] Electrodeposition offers important advantages in 2D material production over other methods such as chemical vapor deposition (CVD), [9,10] sputtering, [11] or atomic layer deposition (ALD). [12] Electrodeposition is not a lineof-sight deposition method as material growth occurs at electrical contacts and is controlled by electrical potential or current. [13] It can hence be utilized to deposit materials over 3D surfaces including patterned nanostructures of high aspect ratios. [14-17] In addition, electrodeposition is usually performed at room temperature, avoiding harsh environments such as plasma or extremely high temperatures, which can damage pre-existing materials on the substrate, such as graphene electrodes. [7] However, there is an important limitation with electrodeposition that needs to be overcome. This method requires an electrically conductive surface from which materials are traditionally grown vertically. [18] Depositing a semiconductor material on a conductor provides a low resistance current path in planar (opto-) electronic devices such as transistors and photodetectors, thus limiting the use of electrodeposition traditionally to certain vertical device structures or metal interconnects (through the dual damascene process). [19] Prior to the work described herein, this limitation has been a drawback, specifically for developing 2D material based devices where planar structures that exploit the unique 2D properties of the material are the "natural" route forward. [20-23] Creating innovative techniques to electrodeposit planar 2D materials over non-conducting surfaces would solve this limitation and open new routes where the insulator base can be utilized, such as in transistor gating. In the early 1990s, Nishizawa et al. described the electrochemical growth of poly(pyrrole)

Photo-conducting CdS films were coated on glass at 450 °C using cadmium chloride and thiourea as Cd and S sources, respectively, with different concentrations. The sprayed CdS films are crystallized in the hexagonal structure and orienting along (0 0 2) plane with good adherence. All the films have high optical absorption in the visible region showing optical bandgap values in the range of 2.39-2.43 eV. The variation of precursor alters the surface morphology of the films. The formed grains are uniformly spread over the substrate and highly agglomerated at 0.15 M concentration. Band to band emission and defect-related emission are reported using photoluminescence (PL) measurements. The CdS device shows relatively high photosensitivity of 0.4 A/W, detectivity of 8.46 × 10 10 Jones, external quantum efficiency (EQE of 140%) with a rise time about 0.2 s and decay time about 0.3 s. These results propose that the CdS thin films are potential candidates for the visible photo-detector applications prepared using an easy and low-cost fabrication method.

The light detection efficiency of Photon detecting components is very much dependent on the operating temperature. Rise in operating temperature reduces their ability of photon detection and reduced output signal. This effect becomes prominent in the cases where very weak signals are needed to be detected. There are various methods which can be applied to cater for the situation of changing ambient temperature or the temperature of the component itself. This study present a method which tracks the temperature changes as seen by the device and hence adjusts the bias voltage being supplied to it. The bias voltage mainly depends upon the temperature coefficient of the component and hence adjusts itself. Design and testing method of bias power supply are presented along with the graphical presentation of result. Streszczenie. Pomiar światła przy wykorzystaniu fotodiody bardzo zależy od temperatury-szczególnie w przypadku małego sygnału wyjściowego. W zaproponowanym układzie zasilania zmienia się napięcie w zależności od temperaury. Obwód zasilania fotodiody z kompensacją temperatury Introduction Temperature compensation becomes necessary in situations where the ambient temperatures keep varying or the components itself are prone to temperature changes as their operation goes along[1]. The situation effects the overall operation of electronic circuitry in terms that required output keep changing drastically. In this regard several approaches have been adopted by researchers, these pertain to use of Zener diodes, Peltier elements and N-JFETs [2] as reference for compensation. Nishida etal also presented a temperature compensation model to work with avalanche photodiodes [3], whereas,Webb et al [4] claimed a quantum efficiency of up to 100% after carrying out temperature compensation for an RAPD. Tajammal and Nagi [5] presented a temperature compensation solution for laser diodes.

A quantitative theoretical analysis of the quadrant photodetector (QPD) sensitivity in position measurement is presented. The Gaussian light spot irradiance distribution on the QPD surface was assumed to meet most of the real-life applications of this sensor. As the result of the mathematical treatment of the problem, we obtained, in a closed form, the sensitivity function versus the ratio of the light spot 1=e radius and the QPD radius. The obtained result is valid for the full range of the ratios. To check the influence of the finite light spot radius on the interaxis cross talk and linearity, we also performed a mathematical analysis to quantitatively measure these types of errors. An optimal range of the ratio of light spot radius and QPD radius has been found to simultaneously achieve low interaxis cross talk and high linearity of the sensor.

Second generation infrared (IR) detectors are now mature at the production level. These detectors are mostly based on HgCdTe (MCT) materials technology. The main second generation detectors at the mass production level are the 288 ¥ 4 long wave length for most of the European forward-looking infrared (FLIR) and the 480 ¥ 6 long wave length for the U.S. Army SADA applications. As far as the 288 ¥ 4 is concerned, SOFRADIR has delivered more than 3000 units already and the market is estimated to be 15,000 units at least! The market is also very large for SADA II units and SOFRADIR has produced them since the end of 1999. Thus, SOFRADIR produces large quantities of mercury cadmium telluride (MCT) detectors and has a unique experience for MCT detectors in mass production. MCT materials technology challenges for mass production concern the main following issues: Quality and reproducibility, MCT wafer size increase, array yield level increase, and the collective manufacturing approach. These issues are discussed in detail in this paper as well as future trends.

Two-dimensional transition metal dichalcogenides have attracted much attention in the field of optoelectronics due to their tunable bandgaps, strong interaction with light and tremendous capability for developing diverse van der Waals heterostructures with other nanomaterials.

A new optical technique for microwave single sideband modulation is reported. It uses metal-semiconductor-metal Schottky photodiodes formed in a GaAs/Al0.3Ga0.7As materials system to detect microwave in-phase and quadrature signals on optical carriers. Modulation of the photodetector bias voltages results in a single sideband modulation of the microwave signal, rf and undesired-sideband suppression of 36 dB and 27 dB, respectively, were achieved. The optical wavelength was 850 nm, and the bandwidth of the photodetectors is greater than or equal to 29 GHz.

A new optical technique for microwave single sideband modulation is reported. It uses metal-semiconductor-metal Schottky photodiodes formed in a GaAs/Al0.3Ga0.7As materials system to detect microwave in-phase and quadrature signals on optical carriers. Modulation of the photodetector bias voltages results in a single sideband modulation of the microwave signal, rf and undesired-sideband suppression of 36 dB and 27 dB, respectively, were achieved. The optical wavelength was 850 nm, and the bandwidth of the photodetectors is greater than or equal to 29 GHz.

Absiruct-We present analytical expressions for the frequency response of avalanche photodetectors (APD's) with separate absorption and multiplication regions (SAM). The effect of the electric field profile in the multiplication layer on frequency response is considered for the first time. Previous theories have assumed that the multiplication layer is very thin and the peak electric field, which corresponds to the effective multiplication plane, is positioned away from the absorption layer. This is a poor assumption for many devices, and in particular for silicon hetero-interface photodetectors (SHIP'S). We present a theoretical model in which the thickness of the multiplication layer is arbitrary and the peak electric field may be positioned arbitrarily in relation to the absorption layer. We also consider the effects of parasitics, transit-time, and avalanche buildup time. Both front and back illumination from either multiplication layer or absorption layer are considered. The calculated results are compared with experimental results for existing SHIP's and performance predictions are also made for optimized SHIP structures. SHIP APD's with gain-bandwidth product in excess of 500 GHz are possible.

—To date, the photodiode still the first choice component is used in optical communication, especially for visible light communication (VLC) system. It has advantages of speed, energy consumption, and sensitivity, compared to other devices (e.g. image sensor). There are many practical implementations of high-speed VLC which uses photodiode. Commercially available photodiode typically have specific characteristics, so that it needs some consideration to be used as optimal receiver devices in VLC system. In this paper, analysis of received power characteristics of the photodiode in indoor line-of-sight (LoS) channel of VLC system is discussed. MATLAB® simulation is used as approach model (student version). The experiments are done by changing several parameters such as the semi-angle half power of the transmitter, distance from the transmitter to receiver, room size, field-of-view (FOV), lens index and optical filter gain. From the results, it can be known that distance, room size, FOV and LED power factor to have linear characteristic against the received power of commercial photodiode. Also in LoS channel model, the gain of optical filter and lens index plays an important role in defining the characteristics of received power.

We present a self-powered, high-performance graphene-enhanced ultraviolet silicon Schottky photodetector. Different from traditional transparent electrodes, such as indium tin oxides or ultra-thin metals, the unique ultraviolet absorption property of graphene leads to long carrier life time of hot electrons that can contribute to the photocurrent or potential carrier-multiplication. Our proposed structure boosts the internal quantum efficiency over 100%, approaching the upper-limit of silicon-based ultraviolet photodetector. In the near-ultraviolet and mid-ultraviolet spectral region, the proposed ultraviolet photodetector exhibits high performance at zero-biasing (self-powered) mode, including high photo-responsivity (0.2 A W−1), fast time response (5 ns), high specific detectivity (1.6 × 1013 Jones), and internal quantum efficiency greater than 100%. Further, the photo-responsivity is larger than 0.14 A W−1 in wavelength range from 200 to 400 nm, comparable to that of state-of-the-art Si, GaN, SiC Schottky photodetectors. The photodetectors exhibit stable operations in the ambient condition even 2 years after fabrication, showing great potential in practical applications, such as wearable devices, communication, and “dissipation-less” remote sensor networks.

Two of the key challenges in the realisation of focal plane arrays based on type-II InAs/GaSb superlattices (T2SL) are the difficulty in achieving a good sidewall profile and the increased dominance of surface leakage current as the device dimensions shrink. We report the electrical and morphological results of test pixels for mid-wave infrared T2SL photodiodes etched using a Cl2/Ar based inductively coupled plasma reactive ion etching (ICP-RIE) process and passivated using SU-8 epoxy photoresist. The etch rate and sidewall surface morphology of GaSb, InAs, and InAs/GaSb T2SL materials are compared after dry etching under the same conditions, leading to the determination of an optimal etch rate. The effect of surface treatment using selected wet chemical etchants before passivation on the surface leakage current is presented. Limitations of the dry etching recipe and further improvement of the sidewall verticality and smoothness are also discussed. Good sidewall profiles and bulk-limited dark currents are demonstrated for T2SL photodiodes etched to depths between 1.5 and 3.5 μm with a pitch size down to 12 μm.

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At present, uncooled thermal detector focal plane arrays are successfully used in staring thermal imagers. However, the performance of thermal detectors is modest, they suffer from slow response and they are not very useful in applications requiring multispectral detection.

We present the design, fabrication, and results from the first monolithically integrated optical phase-locked loop (OPLL) photonic integrated circuit (PIC) suitable for a variety of homodyne and offset phase locking applications. This InP-based PIC contains two sampled-grating distributed reflector (SG-DBR) lasers, semiconductor optical amplifiers (SOAs), phase modulators, balanced photodetectors, and multimode interference (MMI)-couplers and splitters. The SG-DBR lasers have more than 5 THz of frequency tuning range and can generate a coherent beat for a wide spectrum of frequencies. In addition, the SG-DBR lasers have large tuning sensitivities and do not exhibit any phase inversion over the frequency modulation bandwidths making them ideal for use as current controlled oscillators in feedback loops. These SG-DBR lasers have wide linewidths and require high feedback loop bandwidths in order to be used in OPLLs. This is made possible using photonic integration which provides low cost, easy to package compact loops with low feedback latencies. In this paper, we present two experiments to demonstrate proof-of-concept operation of the OPLL-PIC: homodyne locking and offset locking of the SG-DBR lasers.

Asymmetric twin-waveguide (ATG) technology has been shown to be a versatile and high-performance platform for the integration of a wide range of photonic integrated circuits. Following the conceptual and theoretical description in the preceding paper, here we discuss several archetype ATG-based photonic integrated devices and circuits. We present results on the three basic device classes that span the entire range of photonic component needs: light emitters, detectors, and light transporting devices (e.g., waveguides) that have been realized using the twin waveguide platform. Specifically, we discuss Fabry-Pe´rot and wavelength-tunable lasers, high-bandwidth p-i-n photodiodes, a polarization-insensitive arrayed waveguide grating receiver with integrated p-i-n photodiodes, as well as combinations of functions including integrated electroabsorption-modulated lasers, and a semiconductor optical amplifier integrated with a p-i-n photodiode. Finally, we address potential integration challenges and novel applications of the ATG scheme, and avenues for improvement.

Pristine and neodymium-doped (3, 6, and 9 wt.%) ZnO nanostructured thin films were deposited on glass sub-strates using the chemical bath technique. The changes in structural, topographical, photoluminescence, and UV detection properties have been studied. XRD studies confirmed the ZnO phase with a hexagonal structure with a strong prevalence of (002) peak. Nd-doping reduces the bandgap value of the grown material from 3.33 to 3.18 eV. The photoluminescence studies of grown nanowires exhibited the presence of luminescence centers at 387, 412, 438, 452, 477, and 525 nm, respectively. The photocurrent value is increased from 5.37 × 10 − 7 to 3.77 × 10 − 6 A on increasing the Nd doping content from 0 to 6%. The Responsivity, External quantum efficiency, and Detectivity of pristine and doped samples were also studied. We found that the 6% Nd-doped sample shows improved values of optoelectronic parameters which indicate that it is a potential candidate for photodetector applications.

We report on the design and implementation of a fluorescence measurement and analysis device that can identify fluorophore substances. The device performs multi-spectral fluorescence measurements, obtained by exciting the unknown substance with light emitting diodes (LED) whose intensity is CDMA coded for noise rejection. The acquired fluorescence data are processed by a CDMA receiver and a neural network for spectral signature identification and measurement. The design's front end exploits the capability of color LEDs to act as photodetectors with different spectral responses when reverse-biased. The system avoids using optical lenses and is implemented as a minimum chip count design where an FPGA performs all of the required processing with the exception of the analog front end. It is thus appropriate for field use.

The main aim of this work is to investigate the real CMOS imaging possibilities of standard (not CMOS imaging enhanced) 0.5µm and 0.35µm CMOS processes available for in-house fabrication at the Fraunhofer IMS by performing an extensive study of standard available photodetector structures, mainly based on reverse biased p-n junctions and/or metal-oxide-semiconductor capacitors (MOS-C). Moreover, novel concepts of photodetector pixel structures and readout circuits are proposed, modelled, simulated, fabricated, and characterised, that should achieve an improvement in performance as well as new application developments in the area of CMOS imaging systems. The latter, undergoing as a small amount of changes (extra masks, thermal steps, ion implantations, etc.) as possible within the standard CMOS processes mentioned. In this sense, in Chapter 1 a brief review of the fundamentals of silicon oriented photodetection and electronic devices physics is given, some of the basic postulates of w...

The performance of three types of InGaAs/InP avalanche photodiodes is investigated for photon counting at 1550 nm in the temperature range of thermoelectric cooling. The best one yields a dark count probability of $% 2.8\cdot 10^{-5}$ per gate (2.4 ns) at a detection efficiency of 10% and a temperature of -60C. The afterpulse probability and the timing jitter are also studied. The results obtained are compared with those of other papers and applied to the simulation of a quantum key distribution system. An error rate of 10% would be obtained after 54 kilometers.

Layered semiconductors of the IIIA-VIA group have attracted considerable attention in (opto)electronic applications thanks to their atomically thin structures and their thickness-dependent optical and electronic properties, which promise ultrafast response and high sensitivity. In particular, 2D indium selenide (InSe) has emerged as a promising candidate for the realization of thin-film field effect transistors and phototransistors due to its high intrinsic mobility (>10 2 cm 2 V −1 s −1) and the direct optical transitions in an energy range suitable for visible and near-infrared light detection. A key requirement for the exploitation of large-scale (opto)electronic applications relies on the development of low-cost and industrially relevant 2D material production processes, such as liquid phase exfoliation, combined with the availability of high-throughput device fabrication methods. Here, a β polymorph of indium selenide (β-InSe) is exfoliated in isopropanol and spray-coated InSe-based photodetectors are demonstrated, exhibiting high responsivity to visible light (maximum value of 274 A W −1 under blue excitation 455 nm) and fast response time (15 ms). The devices show a gate-dependent conduction with an n-channel transistor behavior. Overall, this study establishes that liquid phase exfoliated β-InSe is a valid candidate for printed high-performance photodetectors, which is critical for the development of industrial-scale 2D material-based optoelectronic devices.

Smart lighting research traditionally focuses on conventional incandescent and fluorescent luminaries. However, in addition to its higher energy efficiency and longer lifetime, Solid State Lighting (SSL) offers better control of spectral, spatial, temporal polarization, and color properties of light. Combined with the recent developments in smart environments research, SSL utilizing Light Emitting Diodes (LED) creates a new playground for user-light interaction. We present a novel illumination model for SSL and implement this model on a wireless sensor network (WSN). The light sensors and actuators in the WSN provide services for sensing illumination changes and dynamically adjusting luminary brightness according to user preferences. Experiments conducted two key scenarios, i.e. reading and watching TV, show that the preferred illumination levels in an activity space can be achieved and maintained, irrespective of external light variations 1 .

Asymmetric twin-waveguide (ATG) technology has been shown to be a versatile and high-performance platform for the integration of a wide range of photonic integrated circuits. Following the conceptual and theoretical description in the preceding paper, here we discuss several archetype ATG-based photonic integrated devices and circuits. We present results on the three basic device classes that span the entire range of photonic component needs: light emitters, detectors, and light transporting devices (e.g., waveguides) that have been realized using the twin waveguide platform. Specifically, we discuss Fabry-Pérot and wavelength-tunable lasers, high-bandwidth p-i-n photodiodes, a polarization-insensitive arrayed waveguide grating receiver with integrated p-i-n photodiodes, as well as combinations of functions including integrated electroabsorption-modulated lasers, and a semiconductor optical amplifier integrated with a p-i-n photodiode. Finally, we address potential integration challenges and novel applications of the ATG scheme, and avenues for improvement.