Si PIN Diodes Research Articles

Comparison of Si and SiC diodes during operationin three-phase inverter driving ac induction motor

4H-SiC JBS diodes have been used in an inverter circuit, driving an actual three-phase ac induction motor at power levels up to 2.2 HP. Switching waveforms were measured and compared between inverters based on Si PiN diodes and 4H-SiC MPS diodes. The results clearly show a significant reduction in power dissipation, in both the diode and the IGBT switch, when SiC diodes replace the Si diodes. The reduction is most evident at the higher temperatures.

Monolithic integration of Si-PIN diodes and n-channel double-gate JFET's for room temperature X-ray spectroscopy

We report on Junction Field Effect Transistors and PIN diodes monolithically integrated on high-resistivity silicon by adopting a non-standard technology recently developed at IRST. In particular, a test structure, consisting of a small PIN diode DC-coupled to an integrated n-channel JFET in the double-gate configuration was fully characterised and spectroscopic measurements were carried out by adopting a novel double-feedback charge amplifier circuit. An ENC of about 60 electrons r.m.s. has been obtained at room temperature and at 10 μs shaping time; such a resolution is shown to be determined by the relatively high total capacitance present in this preliminary set-up, associated with the 1/ f series noise of the transistor.

Soft X-Ray Emission Optimization Study with Nitrogen Gas in a 1.2 kJ Plasma Focus

Measurement of soft x-ray emission from a low-energy plasma focus operated with nitrogen within the pressure range of 0.1–1.0 mbar is presented. The x-rays are detected by using an assembly of Quantrad Si PIN-diodes with differential filtering and with a multipinhole camera. In the 1.0–1.3 keV and 1.0–1.5 keV windows, the x-ray yield in 4π geometry is 1.03 J and 14.0 J, respectively, at a filling pressure of 0.25 mbar and the corresponding efficiencies are 0.04% and 1.22%. The total x-ray emission in 4π geometry is estimated at 21.8 J, which corresponds to the system efficiency of about 1.9%. The soft x-ray emission is found dominantly as a result of electron beam activity on the anode tip, which is confirmed by the images recorded by a pinhole camera.

Component selection for a compact micro‐XRF spectrometer

AbstractThe performances of a number of commercially available components which together can be employed to assemble a compact micro‐XRF spectrometer were compared. The purpose of such a spectrometer is to permit local, non‐destructive analysis of various materials; its compact nature will allow it to be used on‐site, i.e. at the location where the investigated objects/materials are present rather than in a laboratory. The performances of two polycapillary lenses (of different manufacture) and one monocapillary tube were compared in combination with a mini‐focus x‐ray tube with Mo anode. The use of an Si‐drift chamber and an Si PIN‐diode detector was investigated and the achievable minimum detection limits for trace elements in glass and silver matrices were determined. Finally, the effect of using mini‐focus tubes (with 250 µm focus) as opposed to the use of a more conventional x‐ray source (1 mm focus) on the obtained beam size was investigated. Copyright © 2001 John Wiley & Sons, Ltd.

Optical fiber telemetry systems for measurement-while-drilling applications

Two rugged optical fiber telemetry systems for coiled-tubing drilling and other hostile-environment applications are briefly described. One system is a passive uplink; the other is an active simplex link. The transmitter and receiver of the passive uplink are located on the surface. A high-temperature fiber cable connects a serial array of downhole modulators with the surface. Each modulator consists of an intrinsic fiber Bragg grating fixed to a piezoelectric transducer. The simplex link consists of commercial off-the-shelf components: a LED, plastic-clad silica fiber, and a Si pin diode. Both systems performed well when tested at temperatures to 150°C and at vibration levels similar to those downhole. The passive uplink system's performance was unchanged after being tested in actual drilling operations (rotating, drilling, and reaming). The active simplex link's performance was unchanged after being tested at peak vibration levels of 20g. The signal-to-noise ratio of the passive uplinkwas 108 dB/ ?VHz.

Irradiation tests of photodiodes for the ATLAS SCT readout

Two kinds of photodiodes have been investigated for the ATLAS SCT readout. We present in this paper the results of irradiating bulk and epitaxial Si PIN diodes with 1 MeV-equivalent neutrons and 24 GeV protons. The devices were biased during some of the tests. They were exposed to a fluence of around 2.5 × 10 14 n cm −2 followed by a fluence of approximately 2.5×10 14 p cm −2.

Electroluminescence of strained SiGe/Si selectively grown above the critical thickness for plastic relaxation

Electroluminescence of strained Si0.80Ge0.20/Si(001) pin diodes has been investigated experimentally and by quantitative modeling. The key aspect of this investigation was that by selective epitaxial growth the experimental critical thickness for plastic relaxation (80 nm at Tepi=700 °C and large areas) could be increased in finite pads. SiGe layers with thickness of 60, 72 or 370 nm have been grown within the intrinsic i region of pin structures. Samples free of misfit dislocations revealed electroluminescence with the SiGe no-phonon peak and its transversal optical–phonon replica corresponding to interband transitions. It was found that by increasing the thickness of the SiGe layer the drop in the electroluminescence with increasing temperature could be shifted to higher temperature, so that for the 370 nm thick SiGe sample the emission was observed to persist still at 300 K. Modeling based on drift-diffusion and carrier recombination equations was used to simulate the current–voltage characteristics of the pin diodes and their band gap electroluminescence. It was found that the modeling results can account for the temperature and thickness dependence of the electroluminescence. Hole and electron Shockley–Read–Hall recombination times could be evaluated.

Pulse height analysis using Si-pin diode of x-ray irradiated from a 2.45 GHz electron cyclotron resonance multicharged ion source

Production of multicharged ions is experimentally studied on an electron cyclotron resonance (ECR) source. The ECR zone for a microwave frequency of 2.45 GHz is formed at the bottom of a mirror trap. The x-ray spectra are measured by Si-pin diode detector in the various operating conditions. Available energy range of the x-ray measurement is several keV approximately several tens keV. Measurements are carried out at either line of sight including the ECR zone along the geometrical axis or at off-ECR zone from the side wall. The temperatures determined at both positions are about 2–3 keV from the observed spectrum with assuming nonrelativistic maxwellian plasma. The intensities of Ar Kα and bremsstrahlung radiation correlate to pressure and microwave power dependence of multicharged-ion production. But the dependence of the temperature is not clear. Therefore the multicharged-ion production largely depends on an abundance of high energy electrons rather than the change of the temperature of them in this energy region; and it is suggested that the emission profiles of the x-ray radiation peaks at the center of the mirror at the low pressure.

Energy dependence of damage to Si PIN diodes exposed to β radiation

The radiation damage to Si PIN diodes such as used in the OPAL SiW luminometer was studied. It was found that the increase in leakage current after exposure to bursts of 500 MeV electrons is >0.2 × 10 3 times higher than after the exposure of an equivalent dose of electrons emitted from a Strontium β source. Highly-energetic electrons produce a similar amount of damage to silicon as do protons or neutrons.

Polarimeter for soft x rays (abstract)

During the past few years the magnetic circular dichroism effect (MCD) has become an increasingly important tool for studying magnetic materials and their surfaces. The employment of MCD is based on the use of circularly polarized soft x rays, which can be obtained from electron storage rings. Circularly polarized x rays appear either as off-plane bending magnet radiation or radiation from special undulator devices, e.g., crossed or helical ones. However, an unsolved problem has been the independent and simple measurement of the polarization of this radiation. At BESSY, we have developed a new compact polarimeter. The instrument consists of four major elements. There are (i) a pinhole to select the desired part of the photon emission cone and (ii) a 100-period Cr/C multilayer to serve as a monochromator with a spectral resolution power of 50. The angle of incidence is set to 15.9° to meet 718 eV photon energy that corresponds to a maximum MCD effect close to the Fe 2p threshold excitation energy. There are also (iii) a 50 nm Fe film on 3 μm Mylar foil to show the MCD effect in photon transmission (the foil is mounted under 45° to the photon beam and can be magnetized in the plane of the Fe film) and (iv) a Si-pin diode to measure the transmitted photon flux. The assembly fulfills the following requirements: (1) insensitive to linearly polarized and unpolarized light, (2) performance at high heat load, (3) reliability and long term stability also in air, (4) wavelength sensitivity, and (5) fast readout capability. In future work the polarimeter can be employed for the characterization of helical undulators such as the BESSY II UE56, which cover the range of the Fe 2p threshold. With foils of other transition metal or rare-earth materials, the sensitive photon energy range can be extended.

Comparison between performances of optical gratings and Si-PIN detectors in soft x-ray (2 - 7 keV) spectroscopy

In soft x-ray spectroscopy the region from 2 to 7 keV is the most critical, because optical gratings are considered to become inefficient and solid-state detectors exhibit a relatively low energy resolution. We investigated the performances of ion-etched blazed gratings and of silicon detectors as components for soft x-ray spectroscopy. The gratings were mounted in a Rowland geometry at angles of incidence varying from to . We used a microfocus soft x-ray as source and as the detector an uncoated channel electron multiplier sliding along the Rowland circle to scan the spectrum. We recorded several spectra between 2 and 7 keV. The spectral resolution obtained shows essentially almost slit limited line widths; the diffraction efficiency ranges from 1 to 3% at and up to 4.2% at . As a comparison, we recorded the same spectra with a Si-PIN diode, cooled at by a Peltier circuit. The diode exhibits good sensitivity and low noise; the resolution obtained is around 280 eV, almost constant at the various energies. This experiment shows that it is possible to extend the classical spectroscopic techniques to the soft x-ray region in order to obtain complementary performances with respect to solid-state detectors.

Avalanche injection in high voltage Si PiN diodes

An experimental technique using optical excitation by a YAG laser pulse for studying avalanche injection in power devices is demonstrated. This technique enables the creation of high uniform excess carrier concentrations in an optically defined device volume, involving very little heating. A method for determining the onset of avalanche multiplication, by studying the time integral of the reverse recovery current, is proposed. A PiN diode is observed to turn off from avalanching at a dissipated power density of more than 200 kW/cm2.

Impact ionisation in Si bipolar devices

A new theory of impact ionisation recently developed by the author is applied to breakdown in Si pin diodes and collectors of advanced bipolar transistors. Nonlocal aspects dominate the ionisation on short length scales, and good agreement is achieved between the theory and published breakdown and multiplication data.

New, high performance nuclear spectroscopy system using Si-PIN diodes and CdTe detectors

A compact, high resolution X-ray and gamma ray spectroscopy system has recently been developed which provides excellent energy resolution over a wide range of photon energies. Two detector types have been tested, a cooled silicon PIN photodiode for X-ray energies from 2keV to 30 keV and a CdTe detector for energies from 20 keV to 1 MeV. The CdTe detector can be operated cooled or at room temperature. The heart of the system is a miniature preamplifier developed at AMPTEK which is used in combination with a small thermoelectric cooler to reduce the leakage current of the detectors. Using the cooled Si-PIN detector, 660 eV FWHM was achieved at 5.9 keV and using a CdTe detector 1.3 keV was achieved at 60 keV both with nearly 100% counting efficiency. Good resolution was also achieved at higher energies.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The influence of emitter properties on the heat generation in SiC and Si PIN diodes under forward conduction

This study focuses on the impact of the emitters on the forward voltage drop (which affects the heat generation) in Si and 6H-SiC PIN 5kV diodes. The influence of the Shockley-Read-Hall (SRH) lifetime on the forward voltage drop was investigated. It was found that the forward voltage drop of the 5kV Si diode depends much stronger on the SRH lifetime than the 5kV SiC diode. The influence of minority carrier transport in the highly doped emitters on the forward voltage drop in 5kV Si and SiC PIN diodes was quantified. Additionally, two-dimensional simulations of a mesa-etched 5kV PIN diode in 6H-SiC show a large impact of anisotropy on the forward voltage drop at high current densities. These simulations indicate that large advantages with respect to forward voltage drop could be achieved in mesaetched 5kV SiC PIN diodes by choosing the substrate in a direction parallel to the c-axis. This result is interesting since most substrates commercially available today have the polished surface perpendicular to the c-axis.

Soft x-ray output from a laser-produced plasma

X-rays in the 0.5–1.6 keV photon energy range, useful for debris-free damage testing of optical components, are produced efficiently by a laser-produced plasma. Energies exceeding 1 kJ in three beams from the NRL Pharos III laser irradiate a copper target to produce L-shell x-rays from plasma ions. A near-isotropic x-ray fluence of typically 5 cal/cm 2 at 1 cm from the source is deduced from measurements with filtered Si-PIN and biplanar vacuum diodes. The corresponding conversion efficiency of laser to x-ray energy is typically 11%.

Observations of Seeing at 0.5 and 12.4 μm

A variety of observations have been made of solar features (sunspots, faculae, the limb) using both array and single element scanning techniques. The telescope was the 1.6 m McMath-Pierce on Kitt Peak. Array data were acquired with a 58×62 pixel Si:Ga detector at 4.8, 7.8, 12.4, and 18 μm, while a CCD camera recorded the same image position at 0.5 μm. In a separate experiment, a nutating mirror device was used to generate a raster scan of solar disk areas, the output being fed to a Si PIN diode (0.5 μm filter) and a As:Si diode (12.4 μm filter). The scanner data yield simultaneous images at the two wavelengths and was essentially a repeat of the 1970 Turon-Léna experiment with updated equipment. Examples of images at the various wavelengths are given in the poster. Analysis of the data is incomplete at this time. We can report that the effects of seeing were encountered at all wavelengths, including 18μm, even though conditions were deemed good at times (for example, penumbral filaments were resolved in sunspots). We have thus been unable to verify, as yet, the conditions reported by Bester et al, in which exceptional seeing is realized in the infrared.

A semiconductor silicon PIN diode matrix detector for measurement of 133Xe washout in small regional skin areas

Local variations in microvascularization are expected in lesions and lesion-free skin of patients with pressure sores. To investigate these variations, methods for studies of the regional blood flow rate within small skin areas are needed. Regional blood flow can be estimated by measuring the washout of 133Xe from the tissue. The authors describe a 2*12 Si PIN diode matrix detector capable of 133Xe detection, and equipped with a collimator to improve the spatial resolution. Thus the regional blood flow in subcutaneous skin areas down to about 2 cm2 can be investigated when the atraumatic epicutaneous labelling technique is used. The capability of the matrix detector and its collimator is described by laboratory investigations. In pilot investigations three normal subjects and three paraplegics with pressure sores were studied. In each individual study the detector matrix was divided into six square areas containing four diode detectors each. Thus six 133Xe disappearance rate constants from adjacent subcutaneous tissue could be determined simultaneously.

Hybrid phototube with Si target

R & D programmes for future supercollider detectors require photomultipliers that offer high speed, good linearity, wide dynamic range, a good stability and do not need bleeder resistance networks. It has been demonstrated that a hybrid photomultiplier, being a vacuum phototube in which the photoelectrons are focused onto a Si PIN diode, fulfils these requirements. The next step will be a multipixel tube adding position sensitivity to the detector.

Observation of spatio-temporal structures due to current filaments in Si pin diodes

Abstract We present results of spatially and temporally resolved potential-probe measurements arising from the dynamics of current filaments in Si pin diodes due to selfgenerated oscillations. In particular, we detect spatial patterns showing different frequencies or phases of the signal in relation to the external current oscillations.