Performance Of Photodiodes Research Articles

Synthesis and Properties of p-Si/n-Cd1−xAgxO Heterostructure for Transparent Photodiode Devices

We developed silver-doped Cd1–xAgxO thin films (where x = 0, 0.01, 0.02, 0.03 and 0.04) on amorphous glass substrate by an automated nebulizer spray pyrolysis set-up. The XRD patterns show rock salt cubic crystal structures, and the crystallite sizes vary with respect to Ag doping concentrations. SEM images exhibited a uniform distribution of grains with the addition of Ag; this feature could support the enhancement of electron mobility. The transmittance spectra reveal that all films show high transmittance in the visible region with the observed bandgap of about 2.40 eV. The room temperature photoluminescence (PL) studies show the increase of near-band-edge (NBE) emission of the films prepared by different Ag doping levels, resulting in respective decreases in the bandgaps. The photodiode performance was analyzed for the fabricated p-Si/n-Cd1–xAgxO devices. The responsivity, external quantum efficiency and detectivity of the prepared p-Si/n-Cd1–xAgxO device were investigated. The repeatability of the optimum (3 at.% Ag) photodiode was also studied. The present investigation suggests that Cd1–xAgxO thin films are the potential candidates for various industrial and photodetector applications.

The Study of Dark Currents in HgCdTe Heterostructure Photodiodes

Dark current is the main factor that influences photodiode performance. It should be minimal to reduce noise and ensure a high level of photoelectric parameters. In order to identify the predominant causes of generation–recombination in photodiodes based on a mercury–cadmium–tellurium (MCT) ternary compound in the given voltage range, a calculation model is proposed for dark currents caused by fundamental and other current mechanisms. The components of dark current in photodiodes based on MCT heterostructures grown by molecular beam epitaxy (MBE) and liquid-phase epitaxy (LPE) methods are determined in the reverse bias voltages range from 0 to 40 mV. In the range from 0 to 20 mV, these characteristics are reduced to the diffusion component. When the reverse bias voltage exceeds 30 mV, an increase in the Shockley–Read–Hall (SRH) generation–recombination current and tunneling current through trap levels in the band gap is observed.

NIR photodetector based on p-silicon nanowires/n-cadmium sulfide nanoscale junctions

Heterojunction of p-type silicon nanowire and n-type cadmium sulfide (CdS) nanoparticles have been fabricated by deposition of CdS nanoparticles on chemically etched vertically aligned silicon nanowires (SiNWs). The asymmetric current-voltage (I-V) curves confirm the formation of the p-n junction in the SiNW/CdS heterostructures. The growth time of CdS nanoparticles on SiNWs have been optimized for obtaining the best photodiode performance. Variation of current–voltage characteristics with respect to temperature in the range of 200–300 K is also studied and the consequent changes in the barrier height and ideality factor of the p-n junction are observed. Furthermore, from the wavelength vs. current characteristics, the highest current is observed at the near-infrared (NIR) region of the wavelength making it suitable as an NIR detector. The maximum photocurrent (Ip/Id) is calculated to be 6.7 times to dark-current due to photogenerated charge carriers by absorption of photon-energy. The responsivity and detectivity with the variation of light intensities are investigated and the highest values attained by the synthesized samples are 821 mA/W and 1.21 × 1012 Jones respectively, for an NIR source having wavelength of ~ 900 nm and intensity of ~ 8 mW/cm2. Thus SiNW/CdS film can be introduced as a probable candidate for a photo-electronic application.

Application of Bpw34 photodiode and cold white LED as diagnostic X-ray detectors: A comparative analysis

This study compares the real-time dosimetric performance of a bpw34 photodiode (PD) and cold white light-emitting diodes (LEDs) based on diagnostic X-ray-induced signals. Signals were extracted when both the transducers were under identical exposure settings, including source-to-detector distance (SDD), tube voltage (kVp), and current-time product (mAs). The transducers were in a photovoltaic configuration, and black vinyl tape was applied on transducer active areas as a form of optical shielding. X-ray beam spectra and energies were simulated using Matlab-based Spektr functions. Transducer performance analysis was based on signal linearity to mAs and air kerma, and sensitivity dependence on absorbed dose, energy, and dose rate. Bpw34 PD and cold white LED output signals were 84.8% and 85.5% precise, respectively. PD signals were 94.7% linear to mAs, whereas LED signals were 91.9%. PD and LED signal linearity to dose coefficients were 0.9397 and 0.9128, respectively. Both transducers exhibited similar dose and energy dependence. However, cold white LEDs were 0.73% less dose rate dependent than the bpw34 PD. Cold white LEDs demonstrated potential in detecting diagnostic X-rays because their performance was similar to that of the bpw34 PD. Moreover, the cold white LED array's dosimetric response was independent of the heel effect. Although cold white LED signals were lower than bpw34 PD signals, they were quantifiable and electronically amplifiable.

Enhancing Performance of GaAs Photodiodes via Monolithic Integration of Self‐Formed Graphene Quantum Dots and Antireflection Surface Texturing

III–V semiconductor‐based photodiodes with graphene incorporated have been studied in recent years due to the attractive optoelectronic properties of graphene, including optical transparency and enhanced photoresponsivity. The photoresponsivity can be further improved by converting the semiconductor surface into a 3D antireflection (AR) structure. However, difficulties in transferring graphene on top of structured surfaces degrade the interfacial quality and limit their photoresponsivity. Herein, a high‐performance GaAs photodiode structure with self‐embedded graphene quantum dot (GQD) and simultaneously formed periodic AR 3D surface texturing is reported, all produced by a one‐step wet etching process in a solution of hydrogen fluoride (HF) and potassium permanganate (KMnO4) using graphene as a transparent mask. Compared with the planar counterpart without graphene, the photodiodes demonstrated here show an enhancement of photocurrent by 22 times, photoresponsivity by 25 times, and normalized photocurrent to dark current ratio by approximately two orders of magnitude. The improved photoresponsivity of 9.31 mA W−1 is attributed to the increased absorption from AR texturing and the enhanced heterointerface carrier transfer from GQDs to GaAs. This simple, clean yet effective method enables the monolithic incorporation of graphene and graphene‐derived materials on 3D semiconductor structures for applications across a wide range of wavelengths.

Investigation on image signal receiving performance of photodiodes and solar panel detectors in an underground facility visible light communication system.

For the safety, underground facilities are required to be inspected regularly, especially with image analysis. Traditional wireless and wired transmission techniques have a weakness of limited transmission range in narrow underground environments. In this study, a new image transmission method based on visible light communication (VLC) has been thus proposed. Two types of detectors as an image signal receiver have been tested and discussed in the following experiments. The photodiodes (PDs) are widely used as a common image signal detector in VLC technology, but image signal detection using solar panels (SPs) has not been studied. PDs have a higher sensitivity and faster response time but a limited detection area and high cost. Besides, PDs require the lens to focus light. On the other hand, SPs have much larger optical signal receiving areas and stronger optical signal capture capabilities. They can realize lens-free detection and are inexpensive. These features of PD were firstly verified in experiments with several receiving areas and angles of detectors. The experimental result revealed that PD had better image detection and recovery capabilities than those of SP. Then, we found that a larger receiving area obtained by using double PDs/SPs improved the brightness of the restored image. In a supplementary experiment, the influence of different RGB optical components on VLC, especially the VLC-based image transmission, has been investigated by using two-dimensional Fourier transform frequency analysis. We found that the red optical component significantly increased the intensity and energy of the restored image as the image low-frequency signals were larger than the restored image using ordinary mixed white light, and moreover, the blue optical component decreased the low-frequency part of the image.

Geiger-Mode Operation of AlGaN Avalanche Photodiodes at 255 nm

We report the Geiger mode operation of back-illuminated AlGaN avalanche photodiodes. The devices were fabricated on transparent AlN templates specifically for back-illumination to leverage hole-initiated multiplication. The spectral response was analyzed with a peak detection wavelength of 255 nm with an external quantum efficiency of ~14% at zero bias. Low-photon detection capabilities were demonstrated in devices with areas 25 μm x 25 μm. Single photon detection efficiencies of ~5% were achieved.

Temperature and Silicon Film Thickness Influence on the Operation of Lateral SOI PIN Photodiodes for Detection of Short Wavelengths

This work presents an analysis of the temperature influence on the performance of a lateral thin-film SOI PIN photodiodes when illuminated by low wavelengths, in the range of blue and ultra-violet (UV). Experimental measurements performed from 100K to 400K showed that the optical responsitivity of SOI PIN photodetectors is affected by temperature change, being reduced at low and moderately high temperatures. Two-dimensional numerical simulations showed the same trends as in the experimental results, and were used both to investigate the physical phenomena responsible for the observed behavior as a function of the temperature as well as to predict the influence of silicon film thickness downscaling on the photodetector performance.

Research on dispersion compensation using avalanche photodiode and pin photodiode

AbstractWith the growing demand for usage among Internet users, inventions related to increase in the capacity and bandwidth of transmission channels are more significant nowadays. This continuously growing demand can be fulfilled by using the optical fibre for transmission of signals instead of the wireless mode of transmission, due to the less non‐linearity present in the optical fibre. As every available mode has its own shortcomings so does the optical fibre. It suffers from dispersion and other linearities when long‐distance transmission is considered. Hence, the field of invention is associated with the compensation of dispersion in optical fibre communication at higher bit rates of 50–80 Gbps for longer distances of 120 km. After their compensation, comparison of two photodiodes, that is, pin diode and avalanche photodiode has been done at these distinct bit rates in order to achieve the best suited photodiode. After the complete analysis of simulations in terms of quality factor and bit error rate, it has been observed that at distinct bit rates of 50–80 Gbps, the simulation model using avalanche photodiode exhibits superior performance to that of the pin diode. The comparison results show that the performance of the avalanche photodiode is around 11% better than the pin diode.

Uniform and High Gain GaN p-i-n Ultraviolet APDs Enabled by Beveled-Mesa Edge Termination

In this letter, a beveled-mesa edge termination technology was developed to improve the performance of GaN pi-n ultraviolet avalanche photodiodes (APDs). Simulation results showed that the beveled-mesa is effective in reduction of the electric field at the mesa sidewall. With a photoresist thermal-reflow process, 12°-angle beveled-mesa APDs were fabricated from homoepitaxial p-i-n structures on GaN substrate. The most beneficial property of the beveled-mesa termination is the uniform breakdown-characteristic of the beveled-mesa APDs compared to the vertical-mesa APDs. Record-high VBR uniformity of 95.4 V ± 0.2 V and average avalanche gain up to 3 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> were observed for the beveled-mesa APDs within a linear array across 4 mm side-length. These results indicate the potential of the beveledmesa GaN APD array for ultraviolet light imaging applications.

Plasmon-enhanced photoresponse in Ag-WS2/Si heterojunction

Two-dimensional layered materials offer an exceptional platform for production of high-performance optoelectronic devices owing to inimitable opto-electronic characteristics. Metal/TMDCs Nanocomposites can generate significant attention in photoswitching applications due to plasmonic effect. Herein, Ag-WS2 nanocomposites was synthesized by cost effective production through liquid phase exfoliation and microwave assisted solvothermal reaction for improved photodetection for visible light. The Ag-WS2 nanocomposites have highly crystalline nature and Ag nanoparticles are successfully decorated on WS2 Nanosheets through van der Waals interaction. By knowing the excellent absorption of light by Ag-WS2 nanocomposites, large are photodiode based on Ag-WS2/Si heterostructure was fabricated and exploited rigorously under visible light. The photodiode is found to be exhibiting incredible photoswitching ability including high photoresponsivity of 2.09 A/W, specific detectivity of 6.6 × 1011 Jones, external quantum efficiency of 487%. Although, the performance of photodiode is limited by charge trapping centres, device exhibits self-powered photodetection ability. Additionally, the present results of Ag-WS2/Si photodiode are nicely enhanced compared to previous reports. Finally, the fabricated photodiode advocates huge development in the field of large-area optoelectronics due to optimized material configuration and device structure.

SnO2/ZnO/p-Si and SnO2/TiO2/p-Si heterojunction UV photodiodes prepared using a hydrothermal method

Low dimensional nanostructures (NSs) exhibit superior properties for the fabrication of electronic and optoelectronic devices. The integration of these structures into the semiconductor devices is a novel efficient way to achieve high performance heterojunction UV photodiodes due to the enhanced light harvesting and facilitated charge-transfer. Herein, we report the effect of the type of metal oxide seed layers on the formation of SnO2NSs and the performance of SnO2/p-Si heterojunction UV photodiodes. The seed layers were fabricated by depositing ZnO and TiO2 thin films (TFs) on p-Si substrate by spin-coating method. The synthesis of SnO2NSs on each seed layers was achieved by hydrothermal growth technique. It was found that the morphology of nanostructures and light sensing performance of the heterojunction UV photodiodes were significantly influenced by type of seed layers. The photoresponsivity of our fabricated devices were found to be 68 mA/W for SnO2-NSs/ZnOTF/p-Si (device-1) and 92 mA/W for SnO2-NSs/TiO2-TF/p-Si (device-2). Thus, the device-2 is considered to be a better choice over the device-1 for UV detection applications. This research might shed light on new approaches to boost the performance of the heterojunction UV photodiodes.

Ag nanoparticles-decorated Al-Ga co-doped ZnO based photodiodes

Heterojunction photodiodes of assembling Ag nanoparticles (NPs) onto Al-Ga co-doped ZnO (AGZO)/Si were fabricated via a sol-gel spin coating method. The current-voltage characteristics of the devices measured in the dark and under illuminated conditions demonstrated that the performance of photodiodes was remarkably enhanced via decoration of Ag NPs. This was attributed to the scattering effect of Ag NPs because of their large size. Ultimately, the Ag NPs-decorated devices achieved a rectification ratio of 4513, a photoresponsivity of 0.30 A/W and a photo-to-dark-current ratio of 1016. Compared to the bare device, a substantial improvement of 58 % in the photoresponsivity and 147 % in the photo-to-dark-current ratio were observed for the Ag NPs-decorated device. These results render Ag NPs-decorated AGZO/Si heterojunction photodiodes as promising building blocks of future optoelectronic applications.

Ultrahigh photovoltage responsivity of PEDOT:PSS–silicon hybrid heterojunction photodiodes

Strong inversion at the poly(3,4-ethylenedioxythiophene): polystyrene sulfonate PEDOT:PSS/silicon interface facilitates the separation of excess carriers and obstructs surface recombination, both are of utmost importance for optoelectronic detectors. In this view, low-temperature solution-processed PEDOT:PSS/silicon hybrid heterojunctions possess great potential for light detection applications. We investigate the performance of hybrid PEDOT:PSS/silicon photodetectors following long-period exposure to ambience. In addition, the effect of PEDOT:PSS conductivity on the performance of hybrid heterojunction photodiodes is also explored. In the self-powered photovoltage mode, the hybrid photodiode displays an ultrahigh responsivity of 106 V/W, a noise equivalent power of 10 pW/Hz, and a detectivity up to 1010 Jones. Thermal noise is identified as the main limiting factor in the device performance. The hybrid photodetector demonstrates a desirable stability over long-time storage in air.

Temperature, Silicon Thickness and Intrinsic Length Influence on the Operation of Lateral SOI PIN Photodiodes

This work presents an analysis of the influence of the intrinsic length region (Li) and the thickness of the silicon film (tSi) on the performance of lateral thin-film SOI PIN photodiodes when illuminated by low wavelengths, in the blue and ultraviolet (UV) range. The experimental measurements performed with the wavelengths of 396 nm, 413 nm, and 460 nm in a temperature range of 100 K to 400 K showed that the optical responsivity of the SOI PIN photodetectors has larger dependence on the incident wavelength than on temperatures variation. Two-dimensional numerical simulations showed the same trends as the experimental results as a function of temperature and as a function of wavelength. Numerical simulations were used to investigate the responsivity and total quantum efficiency of PIN SOI photodetectors with intrinsic length region ranging from 5 µm to 30 µm and silicon film thickness ranging between 40 nm to 500 nm. From the results can be concluded that by properly choosing Li and tSi it is possible to optimize PIN SOI photodiodes performance for detecting specific wavelengths.

Influence of rare earth doping concentrations on the properties of spin coated V2O5 thin films and Cu/Nd-V2O5/n-Si Schottky barrier diodes

In the present work, Nd(x)-V2O5-nanorods (x = 2, 4 and 6 wt%) thin films were prepared via a spin coating technique. X-ray diffraction analysis shows tetragonal phases for neodymium substituted films. The concern diffraction angle shifted to higher angle owing to substitution in vanadium that implies complete occupation in V2O5 crystal lattice. FE-SEM images are flaunting one dimensional nano-rod formation. Conductivity analysis of fabricated diode at different temperature reveals their activation energies (Ea) and these energies are high when rare earth interfaced diode in contrast to pure vanadium films. The essential current (I) and voltage (V) characteristics of junction diodes express nonlinear behaviour. The photodiode parameters like n, ФB, I0, Ps, R, QE and D* are calculated by dark and light condition. The photodiode performance under lighting condition is superior than dark.

Silicon-Integrated III–V Light Emitters and Absorbers Using Bipolar Diffusion

The ultimate target for silicon photonics is to merge together all electronic and photonic functions on the same CMOS platform. This requires efficient light emitters and absorbers directly integrated on silicon chips, the lack of which presently forms one of the major bottlenecks for further progress. In this work, a possible solution is presented where diffusion-driven charge transport (DDCT), lateral doping of silicon, and III--V nanowire growth are combined to create fully integrated near-surface light emitters and absorbers controlled solely by biasing the underlying silicon wafer. According to the three-dimensional full-device simulations carried out in this paper, DDCT enables high efficiencies for both light emission and photodiode operation in technically feasible silicon-integrated free-standing nanowire structures. Moreover, the results indicate that DDCT is especially well suited for the commonly used 1.55 $\ensuremath{\mu}\mathrm{m}$ wavelength due to the optimal band-gap difference with silicon, which promotes both a high injection efficiency and low voltage losses.

Schottky junction photodiode based on graphene—organic semiconductor heterostructure

The isolation of graphene on an insulating substrate has provided new opportunities for the fabrication of electronic devices with radically new geometries and structures. The use of single-layer graphene as an electrode has enabled the development of novel electronic device architectures that exploit the unique atomically thin structure of the material, which also includes a low density of states at its charge neutrality point. In this work, we present the first example of a vertical Schottky junction photodiode based on the graphene—organic semiconductor–metal heterostructure. The n-type N,N′-dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C8) organic semiconductor was thermally deposited onto chemical vapor deposition (CVD)-grown single-layer graphene. The tunable Schottky injection barrier permitted tuning of the diode rectification ratio by more than two orders of magnitude upon application of gate biases, which increased the photocurrent but suppressed the dark current of the photodiodes. Tuning of the photovoltaic properties of the devices was also confirmed, indicating that the device architecture based on the work function tunability of graphene could provide a versatile strategy for enhancing the performance of organic photodiodes.

Bio‐interface behaviour of graphene and semiconducting SWCNT:C60blend based nano photodiode for subretinal implant

Hybrid interfaces between living cells and organic conjugated polymers play a pivotal role in bioelectronics medicine. Currently, conjugated polymers are widely utilised for optical stimulation of living cells and other bio-interface applications such as neural probes, cellular scaffolds and biosensors for drug release. In such a work, the authors fabricated and characterised the Nano Photodiode array device for the subretinal implant. However, the authors did not discuss in their report about the biocompatibility of this new device. In this work, the authors manifest that the quintessential graphene electrode and polymer blend of semiconducting single-wall carbon nanotube and C60 fullerene (S-SWCNT:C60) sustains its optoelectronic properties all through the various strides for neural preparation. Further, the studies show that these materials can provide a favourable environment for cell proliferation and a high degree of biocompatibility. PC-12 cells used as a valuable model to validate the biocompatibility were grown successfully onto the S-SWCNT:C60 active layer still preserving its optical and electrical properties. The improved electrical performance of nano photodiode made of graphene, S-SWCNT:C60 established in the previous studies and the excellent bio-interface performance of this nano photodiode shows that the nano photodiode array proposed by the authors is a strong candidate for subretinal implants.

Active layer thickness dependence of optoelectronic performance in CH3NH3PbI3 perovskite-based planar heterojunction photodiodes

This work investigates active layer thickness dependence of the morphology, crystallinity and optoelectronic performance of CH3NH3PbI3 perovskite-based planar heterojunction photodiodes (PDs). Surface morphology, average grain size, and crystalline size were monotonically improved with increasing the perovskite film thickness. However, the device performance was dramatically affected by enlarging the perovskite film thickness. Increasing the perovskite film thickness from 300 nm to 450 nm initially raised the device performance from (detectivity (D): 8.13 x 1010 Jones) to (D: 1.42 x 1012 Jones), as a result of the reduced recombination losses and improved charge transport properties due to the superior surface morphology, larger grain size and improved crystallinity. Nevertheless, the performance drops again (D: 2.0x1011 Jones) when the thickness was increased to 600 nm, which can be attributed to reduced absorbance, increased charge recombination and the reduced collection efficiency. An unexpected reduction in absorbance and exceptionally poor charge collection efficiency can be possibly related to the remnant excess PbI2, as inferred from x-ray diffraction analysis.