Si Photodiode Research Articles

Measurement of the near-infrared fluorescence of the air for the detection of ultra-high-energy cosmic rays

We have investigated the fluorescence emission in the near infrared from the air and its main components, nitrogen and oxygen. The gas was excited by a 95 kV electron beam and the fluorescence light detected by an InGaAs photodiode, sensitive down to about 1700 nm. We have recorded the emission spectra by means of a Fourier Transform Infrared spectrometer. The light yield was also measured by comparing the near infrared signal with the known ultraviolet fluorescence, detected by a Si photodiode. The possibility of using the near infrared fluorescence of the atmosphere to detect ultra-high-energy cosmic rays is discussed, showing the pros and the cons of this novel method.

Analysis on Copper Photocorrosion Induced by Illuminance in Chemical Mechanical Planarization Equipment Using Photodiode and Quartz Crystal Microbalance

Photoassisted corrosion of copper (Cu) was evaluated using a photodiode and a quartz crystal microbalance (QCM). A chip-type silicon (Si) photodiode with a large junction area was used in place of actual Si devices. When the illuminated photodiode was connected to the anode and cathode electrodes in an electrolyte, it worked as a voltage source between the two electrodes, and the corrosion rate was governed by the current between the electrodes. The corrosion rate is nearly proportional to the illuminance at less than 100 lx, and corrosion initiates at an illuminance as low as 1 lx. In the geometrical aspect of the photoassisted corrosion system, the corrosion rate is proportional to the square root of the area ratio of a P-connected Cu line to an N line, and is proportional to the illuminated area of the junction in a photodiode. The wavelength of the illuminating light markedly affects the photoassisted corrosion.

Investigation of light absorption properties and acceptance angles of nanopatternedGZO/a-Si/p + -Si photodiodes

In this work, n-GZO/a:amorphous-Si(i:intrinsic)/p + -Si photodiodes are fabricated. We employed a nanosphere lithographictechnique to obtain nanoscale patterns on either the a-Si(i) orp + -Si surface. As comparedwith the planar n-GZO/p + -Si diode, the devices with nanopatterned a-Si(i) and nanopatternedp + -Si substrates show a 32% and 36.2% enhancement of photoresponsivity. Furthermore, theacceptance angle measurement reveals that the nanostructured photodiodes have largeracceptance angles than the planar structure. It also shows that the device with thenanocone structure has a higher acceptance angle than that with the nanorod structure.

Radiation hardness of optoelectronic components for the optical readout of the ATLAS inner detector

Optical links are used for data transmission of the ATLAS inner detector in a radiation hazard environment at the Large Hadron Collider (LHC). The radiation tolerance is studied for the opto-electronics of GaAs VCSEL and epitaxial Si PIN with 30 and 70 MeV protons at CYRIC. High speed Si and GaAs PIN photo-diodes are also investigated for upgrade to super-LHC. The annealing of GaAs VCSEL by charge injection is characterized. The GaAs devices show approximately linear degradations to fluence. The dependence on proton energy is compared to the Non-Ionizing Energy Loss calculations.

Electroless plating of noble metal nanoparticles for improved performance of silicon photodiodes via surface plasmon resonance

Surface plasmon resonance from noble metal nanoparticles is a promising way to improve the efficiencies of silicon based photodiodes and solar cells. Electroless plating is an extremely simple technique for producing such metallic nanoparticles. It is found that the deposition of gold on Si photodiodes occurs as chains that drastically reduce the photodiodes conversion efficiency. However, silver deposits as nano-islands that are efficient SPR centers, which improve the performance of Si photodiodes in the visible region; as measured by both IPCE and I– V curves. The greatest improvement observed was a 3.5% increase in J sc under solar irradiation. Although this improvement is lost upon annealing it can be regained by a further treatment in acidified HAuCl 4. Possible explanations for these latter two behaviors are proposed.

A rotating-compensator based reflectance difference spectrometer for fast spectroscopic measurements

We present a new type of reflectance difference (RD) spectrometer for fast spectroscopic measurements based on a rotating-compensator (RC) design. The instrument uses a 1024 element Si photodiode linear array for simultaneous multiwavelength detection. High quality RD spectra covering a spectral range from 1.5 to 4.5 eV can be acquired within a few seconds. A detailed description of the working principle, the instrumentation, and the algorithms used for data collection and reduction is presented, followed by a discussion of errors introduced by lamp instability and optical imperfections of the compensator. Finally, to demonstrate the performance of the new RCRD spectrometer, we illustrate its application for the in situ, real-time monitoring of the initial stages of organic thin film growth of para-sexiphenyl (p-6P) on the Cu(110)-(2 x 1)O surface.

CsI(Tl) + photodiode scintillation assemblies for γ-ray and proton detectors

CsI(Tl) crystal + Si photodiode scintillation assemblies have been designed to detect photons with energies of 60–1330 keV and protons with energies of 6–50 MeV. The spectrometric characteristics of the assemblies and their radiation hardness have been investigated. The assemblies are shown to have a high energy resolution: 19.6 and 4.6–5.0% for photons with energies of 59.6 and 662 keV and 3.9 and 1.5% for protons with energies of 10 and 20 MeV, respectively. The radiation hardness of these detectors is rather high: it corresponds to a dose of up to 103 Gy under photon irradiation and fluxes of up to 1012 protons/cm2 under exposure to protons.

Autoconfocal transmission microscopy based on two-photon-induced photocurrent of Si photodiodes

We describe a simple, self-aligned confocal transmission microscopy technique based on two-photon-induced photocurrents of silicon photodiodes. Silicon detectors produce photocurrents in quadratic dependence on incident intensity under the pulsed illumination of light with wavelengths longer than 1.2 microm. We exploit this nonlinear process to reject out-of-focus background and perform depth-sectioning microscopic imaging. We demonstrate a comparable background rejection capability of the technique to linear confocal detection and present three-dimensional imaging in biological specimens.

Photocurrent in Ag–Si photodiodes modulated by plasmonic nanopatterns

We demonstrate that Ag–Si photodiodes allow photocurrents to be modulated by changing periods of nanopatterns on Ag film. The maximum and minimum photocurrents occur in certain periods corresponding to the excitation of surface plasmon polariton and Wood’s anomaly, which can be predicted with the help of related theories. Therefore, it is feasible to design nanopatterns to satisfy special requirements.

Group III-nitride semiconductor Schottky barrier photodiodes for radiometric use in the UV and VUV regions

We have developed Schottky barrier photodiodes of AlN, AlxGa1−xN, GaN and InyGa1−yN grown on n-SiC. Spectral responsivity measurements demonstrate that the devices fabricated have sharp cut-offs with a rejection ratio of over 3 decades and the cut-off wavelength can be varied by changing the alloy or the composition of the alloys. The internal quantum efficiency of an Al0.19Ga0.81N photodiode is estimated to reach 64% around 300 nm. It is also confirmed that the photodiodes do not notably degrade in responsivity to the UV radiant exposure of 5 kJ cm−2 in contrast to Si photodiodes. Characterization on uniformity, temperature dependence and angular response is also conducted and gives satisfactory results for all items. In conclusion, the Schottky barrier photodiodes of AlN, AlxGa1−xN, GaN and InyGa1−yN work properly as expected and look very promising for precise measurements in the VUV and UV regions.

Multiwavelength Photosensor for On-Chip Real-Time Monitoring of Fluorescence and Turbidity

In this paper, we report simultaneous detection of fluorescence and turbidity using a multiwavelength photosensor. The multiwavelength photosensor is fabricated in a 5 µm 1-poly 1-metal p-well complementary metal oxide semiconductor (CMOS) technology. First, to confirm the basic characteristics of the multiwavelength photosensor, the linearity of irradiated intensity and photocurrent, fluorescence detection capability, and turbidity detection capability were separately observed. Then, in the fluorescence detection measurement using a fluorescent dye, a detection limit of DNA concentration of 49.8 nM was determined. Then, the turbidity detection performance was compared with that of a Si photodiode. Finally, the sensor was used for real-time monitoring of DNA amplification using the loop-mediated isothermal amplification (LAMP) method. Owing to its multiwavelength detection, simultaneous changes in fluorescence and turbidity were successfully observed using a single sensor.

Measurement of dysprosium optical constants in the 2-830 eV spectral range using a transmittance method, and compilation of the revised optical constants of lanthanum, terbium, neodymium, and gadolinium

The optical constants beta, delta of the complex refractive index (ñ = 1-delta+ibeta) of Dy were obtained in the 2-830 eV energy range using a novel transmittance method. Si/W/Dy/W films were deposited by dc-magnetron sputtering on Si photodiode substrates, and the transmittance was characterized using synchrotron radiation. The extinction coefficients beta of Dy and the transmittance of a Si capping layer and two W interface barrier layers as functions of energy were solved simultaneously using a nonlinear optimization routine. The measured transmittances of the capping and barrier layers were primarily used as indicators for any flaws in the transmittance results. The dispersion coefficients delta of Dy were calculated using the Kramers-Kronig integral, and a complete set of beta values required for this integral was obtained by combining the present data with data from the literature. Sum rule tests on Dy show some deficiencies in the present data, which may be attributed to lower film density compared with the bulk value. Similar procedures were applied to previously measured transmittances of B4C/La, Si/Tb, Si/Nd, and Si/Gd films, where B4C or Si were used as capping layers on those reactive rare-earth films. The improved sets of transmittance values of B(4)C and Si capping layers were used as input in the optimization routine to solve for more accurate beta values of La, Tb, Nd, and Gd. The revised optical constants of these materials, tested for consistency with partial sum rules, are also reported.

X-pinch x-ray sources driven by a 1μs capacitor discharge

X pinches formed from tungsten, molybdenum, titanium, aluminum, and alloys, such as constantan and nichrome with diameters of 13–25μm, have been imploded with a 300kA, 1μs quarter-period capacitor discharge and observed with an array of diagnostics including time-integrated optical photography, x-ray pinhole cameras, x-ray Si photodiodes, a flat crystal spectrograph, and a Nd:YAG laser interferometry/schlieren system. The results of these comprehensive observations are presented. When a single, central hot spot is formed with the right choice of wire and x-ray filter, it is observed to be highly localized, very bright and small enough that point projection radiography can be routinely demonstrated for a simple biological specimen. For an aluminum X pinch, spectroscopic measurements indicate that the hot spots have a plasma density and electron temperature consistent with ∼1020cm−3 and ∼320–350eV, respectively.

Multianalyte sensor array based on an organic light emitting diode platform

A compact photoluminescence (PL)-based sensor array, utilizing pulsed organic light emitting diode (OLED) pixels as the excitation sources, for sequential or simultaneous detection of multiple analytes in a single sample, is described. The utility and potential advantages of the structurally integrated OLED-based platform for multianalyte detection are demonstrated for oxygen, glucose, lactate, and ethanol. The detection of glucose, lactate, and ethanol is based on monitoring the concentration of dissolved oxygen (DO) at the completion of the enzymatic oxidation reactions of these analytes in sealed cells. The monitoring in sealed cells and the ready access of the enzyme, when in solution, to the analyte enable a limit of detection of ∼0.02 mM, which is better than that obtained with enzymes embedded in sol–gel films. The DO concentration is determined via its effect on the PL decay time of the oxygen-sensitive dye Pt octaethylporphyrin embedded in a polystyrene film. A modified Stern–Volmer equation is derived to generate a linear calibration. The 2 mm × 2 mm OLED pixels and the sensor films are fabricated on glass substrates that are attached back-to-back, generating a compact module devoid of any optical couplers. Two individually addressable OLED pixels are associated with the detection of each analyte. This configuration enables consecutive detection of all analytes within a few minutes utilizing a single photodetector (PD). Simultaneous detection is achieved by using an array of small-size Si photodiode PDs compatible with the OLED pixel array. The OLED-based sensing array is unique in its ease of fabrication and integration with the sensing component, while its performance attributes are comparable to those obtained for detection of a single analyte using any excitation source.

Properties of ZnSe:Te,O Crystals Grown by Bridgman-Stockbarger Method

Zinc selenide crystals were grown in graphite crucibles by the Bridgman–Stockbarger method in a vertical compression furnace under argon pressure of 5×106 Pa. From the absorption spectra, the band gap energies of the ZnSe single crystals were calculated by a linear fitting process. The maximum wavelength of the emission spectrum of the ZnSe:Te,O scintillator was 630 nm, which was well matched with the response wavelength of the Si photodiode. The energy resolution of the ZnSe:Te,O scintillator was 11.9% when it was exposed to 137Cs γ-ray. Its size was 10×10×1 mm3. The afterglow level of the ZnSe:Te,O scintillator after 5 ms was 0.023%. The relative light output of the ZnSe:Te,O scintillator was 2.167 times higher than CsI:Tl. The luminescence decay time of the ZnSe:Te,O scintillator has two exponential components with 27 and 84 γs time constant.

Polarization-transmissive photovoltaic film device consisting of an Si photodiode wire-grid

This paper proposes a polarization-transmissive photovoltaic device, which consists of an Si photodiode wire-grid. Each nanowire is 400 nm in width, 50 µm in length and 5 µm in thickness. The nanowires are spaced 500 nm apart. The device transmits the light polarized in one direction and generates a photocurrent from the light polarized in the other direction. The fabricated device generates a 52 nA photocurrent from 250 µW incident light from a white lamp and achieved an extinction ratio of 4 for the 675 nm laser.

Growth and properties of new ZnSe(Al,O,Te) semiconductor scintillator

The zinc selenide crystals were grown in graphite crucibles by Bridgman–Stockbarger method in vertical compression furnace under argon pressure of 5 × 10 6 Pa . The grown ZnSe(Al,O,Te) single crystals were annealed in a Zn vapor at 1290 K for 24 h. An X-ray diffractometer (XRD) was used to investigate the structural properties of the zinc selenide single crystals. The lattice constants of the ZnSe single crystals were obtained from XRD data. After annealing it in a Zn vapor at 1290 K, it is found that the lattice constant decreases. From the absorption spectra, the band gap energies of the ZnSe single crystals were calculated by a linear fitting process. The band gap energy of the ZnSe(Al,O,Te) single crystal decreases more than that of the ZnSe single crystal. The maximum wavelength of the radioluminescence of the ZnSe(Al,O,Te) scintillator excited by X-ray was 606 nm, which was well matched with the response wavelength of the Si photodiode. The energy resolution of the annealed ZnSe(Al,O,Te) scintillator was 13.9% when it was exposed to 137Cs γ -ray. Its size was 10 × 10 × 1 mm 3 . The afterglow level of the annealed ZnSe(Al,O,Te) scintillator after 5 ms was 0.014%. The luminescence decay time of the annealed ZnSe(Al,O,Te) scintillator has two exponential components with 4 and 12 μ s time constants. The charged particle and the low energy gamma ray can be detected successfully with the annealed ZnSe(Al,O,Te) scintillator. It was investigated that the ZnSe(Al,O,Te) scintillator can be used for the security inspection system.

Bandwidth enhancement in Si photodiode by eliminating slow diffusion photocarriers

The body contact in a Si photodiode fabricated by standard CMOS technology is used to eliminate the slow diffusion photogenerated carriers to enhance the response. The proposed photodiode demonstrates significant reduction in the long tail from pulse measurement and consequently shows the electrical bandwidth of 2.8 GHz and 5 Gbit/s eye diagram.

The development situation of Si photo diodes

The development situation of Si photo diodes

Ge on Si Photodiodes for Si CMOS Monolithic Optical Receivers

We report a Ge growth technique on Si using thin SiGe buffer layers and also discuss photodiodes fabricated on the Ge for Si CMOS monolithic optical receiver applications. The effectiveness of thin SiGe buffer layers in terminating threading dislocations and reducing photodiode dark current for Ge epitaxially grown on Si (001) has been investigated for Ge photodiodes. The dark current of Ge on Si photodiodes can be reduced by over an order of magnitude by incorporating two different composition SiGe buffer layers. A backside- illuminated photodetector has been fabricated with the dark current as low as 3.6 mA/cm2 at 1 V reverse bias. To improve the speed of the photodiode, a device with thinner SiGe buffer layers was demonstrated and achieved 21.5 GHz bandwidth at 1.31 mm, resulting in a record high efficiency-bandwidth product of 12.9 GHz.