Characteristics Of Photodetectors Research Articles

Investigation of the characteristics of matrix multi-element avalanche photodetectors operating in the photon counting mode

At present, matrix multi-element avalanche photodetectors operating in the photon counting mode are widely used for detecting optical radiation. However, the char-acteristics of matrix multi-element avalanche photodetectors operating in this mode are currently insufficiently studied. Prototypes of Si-photomultiplier tubes (Si-PMTs) with a p+–p–n+ structure produced by JSC Integral (Republic of Belarus), as well as serially produced silicon photomultipliers Ketek PM 3325 and ON Semi FC 30035 have been used as objects of research. This article presents the research results of characteristics in the photon counting mode of the specified photodetec-tors. The dependences of the specific amplitude sensitivity ratio on the wavelength of optical radiation, the temperature, the supply voltage of the matrix multi-element avalanche photodetector are determined.

Fourier analysis of spectral characteristics of a matrix photodetector in the frequency and time domain

The purpose of this paper is to research the frequency and time characteristics of the photo-detector using the direct and inverse Fourier transform. The spectral characteristics of the matrix photodetector were selected as the object of research. For the channels of the trans-ducer it was found that the frequency spectrum consists of two elementary bands in the form of Gaussian curves. It was revealed that the spectra have super-broadband properties. The impulse (time) characteristic of the spectra is described by the equation in an analytical form, which is in good agreement with the calculation. The rise time of the transient response is 1.8–2.9 fs. The process of absorption of light is significantly influenced by dielectric relaxa-tion of the charge. The results obtained provide important information on the properties of the photodetector in the frequency and time domain.

Fabrication and properties of a solar-blind ultraviolet photodetector based on Si-doped β-Ga2O3 film grown on p-Si (111) substrate by MOCVD

A solar-blind ultraviolet photodetector based on p-Si/n-β-Ga2O3:Si heterojunction, using the Si-doped β-Ga2O3 as the n-type layer, was fabricated successfully by metal-organic chemical vapor deposition (MOCVD). The current-voltage and photoresponse characteristics of photodetector were investigated. The fabricated p-Si/n-β-Ga2O3:Si heterojunction photodetector exhibited typical rectification behavior and good solar-blind ultraviolet photoresponse. Sensitive photodetection of current at the reverse bias voltage and stable on-off switching performance were achieved. The photodetector showed a responsivity of 3.76 A/W and a photo-to-dark current ratio of 37.9 under 254 nm illumination. The rise time constants (τr1, τr2) and the decay time constants (τd1, τd2) of the photodetector under 254 nm illumination at the reverse voltage of − 20 V were estimated to be (0.30 s, 0.76 s) and (0.15 s, 6.15 s), respectively. The fabricated p-Si/n-β-Ga2O3:Si heterojunction photodetector displayed relatively faster response speed compared to the reported photodetectors based on p-Si/undoped β-Ga2O3 heterojunction. The results indicate that photodetectors based on p-Si/n-β-Ga2O3:Si heterojunction have potential development for the high-performance solar-blind ultraviolet photodetectors.

Ambient stability improvement of CQD photodetectors by low-temperature deposited graphene encapsulation

In this work, we have investigated the ambient stability improvement of colloidal quantum dots (CQD) photodetectors by graphene encapsulation. The low temperature deposited graphene is performed to act as an isolating membrane between PbS CQDs and the ambient environment. The oxidization of PbS CQDs can be significantly inhibited with a graphene isolating membrane. In addition, the optoelectronic characteristics of PbS CQDs-based photodetectors encapsulated by graphene are well maintained even exposed in ambient for a month. This work paves the way for the fabrication and application of the air-stable CQDs.

Modulation characteristics of uncooled graphene photodetectors

We report on the modulation characteristics of the uncooled terahertz (THz) and infrared (IR) detectors using uniform graphene layers (GLs) and perforated graphene layers (PGL). Our analysis shows that the PGL detectors could have more than an order of magnitude smaller dark current compared to more conventional GL reversed biased photodetectors operating in the same frequency range. The modulation mechanism for the simulated photodetectors is the variation of the density and effective temperature of the two-dimensional electron–hole plasma with the varying intensity of the THz or IR radiation. Our simulations predict a reasonable modulation depth up to the modulation frequencies of 50 GHz for the impinging radiation frequencies up to the mid-IR range.

Fabrication and characterization of InN-based metal-semiconductor-metal infrared photodetectors prepared using sol–gel spin coated technique

We report on the growth and characterization of undoped indium nitride (InN) thin films grown on a silicon substrate. The InN thin films were grown on aluminium nitride (AlN) template with gallium nitride (GaN) nucleation layer using a relatively simple and low-cost sol–gel spin coating method. The crystalline structure and optical properties of the deposited films were investigated. X-ray diffraction and Raman results revealed that InN thin films with wurtzite structure were successfully grown. For InN thin film grown on a substrate with the GaN nucleation layer, its strain and dislocation density are lower than that of the substrate with the AlN nucleation layer. From the ultra-violet-visible diffuse reflectance spectrum analysis, the energy bandgap of the InN thin films with the GaN layer was 1.70 eV. The potential application of the sol–gel spin-coated InN thin films was also explored. Metal–semiconductor–metal (MSM) infrared (IR) photodetectors were fabricated by depositing the platinum contacts using two interdigitated electrodes metal mask on the samples. The finding shows that the device demonstrates good sensitivity and repeatability towards IR excitation at a wavelength of 808 nm. The photodetector characteristics at dark and photocurrent conditions such as Schottky barrier height (SBH) and ideality factor are determined. Upon exposure to the IR source at 3V applied bias, InN/AlN/Si device configuration displays rapid rise time of 0.85 s and decay time of 0.78 s, while InN/GaN/AlNSi demonstrates slow rise time of 7.45 s and decay time of 13.75 s.

Signal-to-noise characteristics of graphene photodetectors based on photothermoelectric effect

A sensor using the photothermoelectric effect of graphene is anticipated as a candidate for infrared sensors that can operate at room temperature with fast response and high sensitivity. We investigate photothermoelectric detection and the signal-to-noise characteristics of a sensor with a simple metal–graphene–metal structure numerically and analytically and obtain an analytical expression giving the ideal value of specific detectivity D∗ for a sensor having an ideal potential distribution. It is found that the optimal sensor length is approximately three times longer than the cooling length and that the value of D∗ for such a sensor with typical cooling length is estimated to be as large as 106 cmHz/W. The sensor performance can be greatly enhanced by employing light-confining structures such as cavities and plasmon antennas, achieving D∗ above 108 cmHz/W.

Effect of Pt-doped on the photocurrent of MSM photodetector

This article report the fabrication and characteristics of MSM photo detector by compare between non-doped and doped platinum (Pt) atom. Fabrication process has same but different in Pt doping process for atom doping and diffusion process. The metal finger width 2um with 50 um spacing between metal contact. At bias voltage 10 voltage show higher capacitance-voltage and photocurrent increase after doped with Pt atom. By experiment shows photocurrent increase around 4 times from 45.98 to 197.22 uA at bias 10 voltage by photoluminescence 25,000 lux.

MoS2/h-BN/Graphene Heterostructure and Plasmonic Effect for Self-Powering Photodetector: A Review.

A photodetector converts optical signals to detectable electrical signals. Lately, self-powered photodetectors have been widely studied because of their advantages in device miniaturization and low power consumption, which make them preferable in various applications, especially those related to green technology and flexible electronics. Since self-powered photodetectors do not have an external power supply at zero bias, it is important to ensure that the built-in potential in the device produces a sufficiently thick depletion region that efficiently sweeps the carriers across the junction, resulting in detectable electrical signals even at very low-optical power signals. Therefore, two-dimensional (2D) materials are explored as an alternative to silicon-based active regions in the photodetector. In addition, plasmonic effects coupled with self-powered photodetectors will further enhance light absorption and scattering, which contribute to the improvement of the device’s photocurrent generation. Hence, this review focuses on the employment of 2D materials such as graphene and molybdenum disulfide (MoS2) with the insertion of hexagonal boron nitride (h-BN) and plasmonic nanoparticles. All these approaches have shown performance improvement of photodetectors for self-powering applications. A comprehensive analysis encompassing 2D material characterization, theoretical and numerical modelling, device physics, fabrication and characterization of photodetectors with graphene/MoS2 and graphene/h-BN/MoS2 heterostructures with plasmonic effect is presented with potential leads to new research opportunities.

Solution-Processed Black-Si/Cu2ZnSnS4 Nanocrystal Heterojunctions for Self-Powered Broadband Photodetectors and Photovoltaic Devices

We report, for the first time, the fabrication of n-black Si (B–Si)/p-Cu2ZnSnS4 nanocrystal (CZTS NC) heterojunctions to demonstrate their photodetection and photovoltaic characteristics. Inks with...

Enhanced UV photodetection characteristics of annealed Gd2O3 nanorods

Enhanced UV photodetection characteristics of annealed Gd2O3 nanorods

Basic Characteristics of Photo-Resistive Photodetectors Based on Composite of Poly(3-Hexylthiophene) and Silicon Nanoparticles

Basic Characteristics of Photo-Resistive Photodetectors Based on Composite of Poly(3-Hexylthiophene) and Silicon Nanoparticles

High Figure‐of‐Merit Gallium Oxide UV Photodetector on Silicon by Molecular Beam Epitaxy: A Path toward Monolithic Integration

A high figure‐of‐merit UV‐C solar‐blind photodetector (PD) fabricated from thin‐film beta‐gallium oxide (β‐Ga2O3) grown on n‐Si substrates by plasma‐assisted molecular beam epitaxy is demonstrated. Film growth sequences for nucleation of Ga2O3 on (100)‐ and (111)‐oriented Si substrates are developed, and the influence of crucial growth parameters is systematically investigated, namely, substrate temperature, oxygen flow rate, and plasma power on the functional properties of the PDs. The PDs show an ultra‐high responsivity of 837 A W−1 and a fast ON/OFF time below 4 ms at −5 V. In addition, they display strong rectifying properties and a sharp cutoff below 280 nm with the average responsivities between 10 and 80 A W−1, a detectivity on the order of 1010 Jones, and rise/fall times between 4 and 500 ms. High photoconductive gain is likely to be due to the mid‐bandgap donor/acceptor defect levels, including oxygen vacancies in the form of self‐trapped holes. It is demonstrated that these defect levels can be modified by controlling the growth conditions, thereby allowing for tailoring of the PD characteristics for specific applications. The methodology represents a cost‐effective solution over homoepitaxial approaches, with characteristics that meet or exceed those reported previously, offering new possibilities for on‐wafer integration with Si opto‐electronics.

SnS2/Si nanowire vertical heterostructure for high performance ultra-low power broadband photodetector with excellent detectivity

Nanoparticle–nanowire heterostructures provide a new platform for photodetection applications owing to their higher light absorption, large responsivity, and excellent separation efficiency of photogenerated electron–hole pairs. Herein, we report a SnS2/Si nanowire heterostructure photodetector with excellent optoelectronic properties. A high-quality SnS2/Si nanowire heterostructure was prepared by simply spin coating a wet chemically synthesized SnS2 on a vertically standing Si nanowire made by metal assisted chemical etching. The as-prepared SnS2/Si nanowire heterostructure exhibits a robust p–n junction with excellent photodetector characteristics. The photodetector based on the heterostructure shows a photo-responsivity of ∼3.8 A W−1, a specific detectivity up to ∼ 2 × 1014 Jones, and an on/off ratio up to ∼ 102 at 340 nm illumination wavelength with a significantly low optical power density of 53.75 nW/mm2 at zero bias (0 V). The photo-responsivity reached its maximum value of ∼102 A/W and detectivity of ∼1 × 1014 Jones at the same wavelength with an applied bias of −2 V. In addition, the heterostructure photodetector provides significantly good photodetector key parameters (responsivity ∼5.3 A/W, detectivity ∼ 7.5 × 1012 Jones, rise/decay time ∼0.4/0.4 s) at −2 V bias over a wide spectral range from 400 to 1100 nm. The Si nanowire and SnS2 nanoparticle heterostructure devices with an enhanced junction area open up an exciting field for novel non-toxic and environmental friendly broadband optical detection applications and optoelectronic memory devices with high responsivity, ultrahigh sensitivity, and self-sufficient functionality at low power consumption and low cost with ease of processing.

Influence of the incident optical field distribution on a high-speed PIN photodetector and horizontal optimization.

We demonstrate a new, to the best of our knowledge, dimensional "horizontal optimization" scheme, which can improve the high-speed characteristics of a PIN photodetector by designing the incident optical field distribution. First, coaxially incident faculae with the same peak and same power are studied and simulated, revealing that the bandwidth of the photodetector illuminated by uniform light is higher than that of the device illuminated by nonuniform light. Next, an annular optical field is designed incident to the photodetector, and the bandwidth is further improved. For a PIN photodetector, by carefully optimizing the incident optical field distribution, the photodetector bandwidth under an annular optical field can be increased significantly compared with that under conventional coaxial illumination.

Evaluation of Angle-of-Incidence Characteristics of Plasmonic Photodetector Based on Strain Measurement of Metal Cantilever

This paper reports a measurement system for angle-of-incidence characteristics of a plasmonic photodetector using a strain gauge on a metal cantilever. The photodetector is installed on the metal cantilever equipped with the strain gauge at the root of the cantilever. By deforming the cantilever, the angle of incidence of the photodetector was scanned. This angle of incidence was calculated by measuring the strain on the metal cantilever. The photocurrent signal from the photodetector and the strain signal from the strain gauge were simultaneously measured using an oscilloscope while the cantilever was being deformed. The simultaneous measurement of the two signals produced similar result to the one obtained by a conventional measurement using a rotating stage, indicating that the proposed structure is capable of simultaneous measurement of photocurrent and angle of incidence.

Using Novel Semiconductor Features to Construct Advanced ZnO Nanowires-Based Ultraviolet Photodetectors: A Brief Review

Ultraviolet photodetectors have attracted significant research attention in recent years due to their potential applications in civilian and military fields. ZnO nanowires and nanorods have been regarded as the most potential candidates for ultraviolet photodetectors fabrication because of their peculiar characteristics and size effect, which are different from their bulk material. Recently, many novel routes and semiconductor features, such as the surface and interface engineering, the pryo-phototronic effect, the piezo-phototronic effect, the surface plasmon effect and the surface functionalization have been utilized to improve the photoelectric characteristics of ultraviolet photodetectors. Thus, the working mechanism of these effects existing in ZnO nanowires/nanorods-based ultraviolet photodetectors should be investigated in-depth. In this paper, firstly, the hydrothermal method and the chemical vapor deposition method, as two typical synthesis methods of ZnO nanowires are briefly reviewed. Secondly, we focus on reviewing the properties of varied ZnO nanowires/nanorods-based ultraviolet photodetectors constructed using the above mentioned semiconductor features with metal-semiconductor-metal structure, Schottky barrier structure, vertical p-n heterojunction structure and core-shell heterostructure. Furthermore, the most attractive self-powered ultraviolet photodetectors are systematically reviewed. For various ZnO nanowires/nanorods-based ultraviolet photodetectors, we put the emphasis on the working mechanism of semiconductor features to improve the properties of the photodetectors. Finally, we give an outlook on the future development of ZnO nanowires/nanorods-based ultraviolet photodetectors.

Improving the photodetection and stability of a visible-light QDs/ZnO phototransistor via an Al2O3 additional layer

We have developed a visible-light phototransistor with excellent photodetection characteristics and stability via atomic layer deposition (ALD) to add a thin layer of aluminum oxide (Al2O3) to quantum dot (QD)/zinc oxide (ZnO) films.

Exceptional Responsivity (>6 kA/W) and Dark Current (<70 fA) Tradeoff of n-Ga2O3/p-CuO Quasi-Heterojunction-Based Deep UV Photodetector

Reduction of high dark current has been a challenge for high responsivity photodetector (PD). In this context, the present article demonstrates an ultralow dark current of Ga2O3-based deep ultraviolet (UV)-photodetectors (UV-PDs) with enhanced photoresponses by tailoring a p/n heterojunction. An n- Ga2O3/p-CuO quasi-heterostructure-based deep UV-PDs has been fabricated on a sapphire (0001) substrate using an inexpensive electrospraying technique. After Ga2O3 deposition, platinum (Pt) electrodes ( $\sim 50$ nm) are fabricated as a metal–semiconductor–metal (MSM) device using sputtering. The device exhibits a very low dark current in the order of few fA $(6.94\times 10^{-14}$ A) at 5 V because of the enhanced depletion width at p/n heterojunction and Pt/ Ga2O3 metal–semiconductor contacts, which provides a narrow path for free carriers to travel from one metal contact to other under dark condition. The depletion layers get thinner due to the absorption of UV-photons in the UV-illumination condition. Hence, the photogenerated carriers get a wider channel to get collected at Pt-electrodes. Thus, in addition to ultralow dark current, the device exhibits an extraordinary photodetection characteristics, such as a high responsivity ( $\sim 6.33 \times 10^{3} \mathrm{AW}^{-1}$ ), remarkable phototo-dark current ratio ( $\sim 2.99 \times 10^{6}$ ), very high detectivity ( $\sim 4.44 \times 10^{14} \mathrm{mHz}^{0.5} \mathrm{~W}^{-1}$ ), and exceptional external quantum efficiency of $\sim 3.1 \times 10^{6}$ % at 5 V.

Evaluation And Selection Of Colour Spaces For Digital Systems

The research examined the changing of colour difference by the control colours depending on the choice of colour space when working with matrix photo detector. The spectral characteristics of photo detectors from different manufacturers noticeably differ from each other and from the addition the difference in colour quality between different digital devices. A software method for studying the colour rendition of the image obtained by digital devices based on the selection of an individual colour space for each matrix photo detector is proposed. To analyze and evaluate the capabilities of the spectral characteristics of matrix photo detectors, the control colour method based on the Mansell Atlas was used. The analysis of the obtained parameters of 14 colours was carried out according to various criteria for seven colour spaces: sRGB, AdobeRGB, DCI-P3 RGB, M1N1P1, PAL / SECAM, Wide Gamut RGB, ProPhoto RGB. Also studied the influence of the choice of colour space on the change in the coordinates of the source 6,500 K. Based on the colour differences of the control colours, it is possible to choose the optimal colour space for working with a specific matrix photo detector. The latter will reduce colour distortion at the initial stage of image registration. The ways for improving the colorimetric method of control colours are proposed as applied to digital devices at the software level.