H. Aharoni

Ben-Gurion University of the Negev, Beersheba, Southern District, Israel

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Publications (35)22.85 Total impact

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    ABSTRACT: We report on an increase in emission intensity of up to 10 nW / µm 2 that has been realized with a new novel two junction, diagonal avalanche control and minority carrier injection silicon CMOS light emitting device. The device utilizes a four terminal configuration with two shallow n + p junctions, embedded in a p substrate. One junction is kept in deep avalanche and light emitting mode, while the other junction is forward biased and minority carrier electrons are injected into the avalanching junction. The device has been realized using standard 0.35 µm CMOS design rules and fabrication technology and operates at 9V in the current range 0.1 – 3mA. The optical emission intensity is anout two orders higher than that for previous single junction n + p light emitting junctions. The optical output is about three orders higher than the low frequency detectivity limit of silicon p-i-n detectors of comparable dimensions. The realized characteristics may enable diverse opto-electronic applications in standard CMOS silicon technology based integrated circuitry.
    Proc SPIE 03/2007;
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    ABSTRACT: In this paper, we report on an increase in emission intensity of up to 10 nW/mum2 that has been realized with a new novel two junction, diagonal avalanche control, and minority carrier injection silicon complementary metal-oxide-semiconductor (CMOS) light emitting device (LED). The device utilizes a four-terminal configuration with two embedded shallow n+p junctions in a p substrate. One junction is kept in deep-avalanche and light-emitting mode, while the other junction is forward biased and minority carrier electrons are injected into the avalanching junction. The device has been realized using standard 0.35 mum CMOS design rules and fabrication technology and operates at 9 V in the current range 0.1-3 mA. The optical output power is about one order of magnitude higher for previous single-junction n+p light-emitting devices while the emission intensity is about two orders of magnitude higher than for single-junction devices. The optical output is about three orders of magnitude higher than the low-frequency detectivity limit of silicon p-i-n detectors of comparable dimensions. The realized characteristics may enable diverse optoelectronic applications in standard-CMOS-silicon-technology-based integrated circuitry.
    Japanese Journal of Applied Physics 01/2007; 46. · 1.07 Impact Factor
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    L.W. Snyman, M. du Plessis, H. Aharoni
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    ABSTRACT: We report on the dependency of quantum efficiency of an avalanching silicon n<sup>+</sup>p light emitting junction on current density and on the injection current from an adjacent lying forward biased pn junction. The phenomenon was observed in a three terminal silicon bipolar junction CMOS light emitting device (Si BJ CMOS LED). The total increase in power and quantum conversion efficiency is about three orders of magnitude when compared to earlier published results. The optical emissions are about four orders higher than the low frequency detectivity for silicon CMOS detectors of comparable dimension. Because of its small spot size fabrication capability (1 micron diameter), high speed capability (up to 1 GHz), the devices have numerous potential applications in future CMOS integrated circuitry, hybrid micro-systems and MOEMS.
    Industrial Electronics, 2005. ISIE 2005. Proceedings of the IEEE International Symposium on; 07/2005
  • M. du Plessis, L.W. Snyman, H. Aharoni
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    ABSTRACT: Low-voltage Si-LED operation can be achieved by fabricating devices with heavily doped n<sup>+</sup>p<sup>+</sup>junctions. Differences are observed between high-voltage avalanche and low-voltage field emission LED performance. The low-voltage devices exhibit a non-linear light intensity L vs. reverse current I relationship at low current levels, but a linear dependency at higher currents, compared to the linear behavior of avalanche devices at all current levels. Three regions of operation are identified for the low-voltage field emission LED's, namely L ∝ I<sup>3</sup> at low currents, L ∝ I<sup>2</sup> at medium currents and eventually L ∝ 1 at higher currents. In the low-voltage non-linear region of operation, the shape of the emitted spectrum changes with reverse current. At low reverse current the field emission devices emit more long wavelength radiation than short wavelength radiation. As the reverse current increases, the short wavelength radiation increases relative to the long wavelength radiation, and at higher currents in the linear region of operation the ratio between long and short wavelength radiation remains constant.
    Industrial Electronics, 2005. ISIE 2005. Proceedings of the IEEE International Symposium on; 07/2005
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    ABSTRACT: In this paper we report on the dependency of quantum efficiency of an avalanching light emitting junction on current density and on the injection current from an adjacent lying forward biased junction. In particular, we report on the interpretation of results and modelling of the physical processes responsible for the light emission. The phenomenon was observed in a three terminal silicon bipolar junction CMOS light emitting device (Si BJ CMOS LED). Our observations show that the overall quantum efficiency and light emission from these type of devices can be improved to the 10 -3 regime. The optical emissions is about four orders higher than the low frequency detectivity for silicon CMOS detectors of comparable dimension. The three terminal device also enable modulation of the light emission by a third terminal contact. The device has the potential of being fully integratable with standard CMOS integrated circuitry with no adaptation to the CMOS design and processing procedures.
    Proc SPIE 03/2005;
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    ABSTRACT: Silicon is an indirect bandgap material, but light emission is observed from reverse biased pn junctions. Even though the quantum efficiency is low, it may still be advantageous to use these devices in all-silicon optoelectronic integrated circuits (OICs). In this paper new research results with regard to low-voltage field emission BiCMOS and CMOS two- and multi-terminal Si LEDs are presented. The differences observed between avalanche and low-voltage field emission LED performance are presented. It is shown that the low-voltage devices exhibit a square-law light intensity vs. reverse current non-linearity at low-current levels, but a linear dependency at higher currents, compared to the linear behaviour of avalanche devices at all current levels. The detail spectral characteristics of the field emission devices are investigated, showing that in the non-linear region of operation, the shape of the emitted spectrum changes, with reduced short wavelength generation at lower current levels. Bipolar junction transistor (BJT) multi-terminal devices are also discussed, and the square-law behaviour of these devices is presented.
    Optical Materials 01/2005; · 1.92 Impact Factor
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    ABSTRACT: A dependency of quantum efficiency of nn<sup>+</sup>pp<sup>+</sup> silicon complementary metal-oxide-semiconductor integrated light-emitting devices on the current density through the active device areas is demonstrated. It was observed that an increase in current density from 1.6×10<sup>+2</sup> to 2.2×10<sup>+4</sup> A·cm<sup>-2</sup> through the active regions of silicon n<sup>+</sup>pp<sup>+</sup> light-emitting diodes results in an increase in the external quantum efficiency from 1.6×10<sup>-7</sup> to 5.8×10<sup>-6</sup> (approximately two orders of magnitude). The light intensity correspondingly increase from 10<sup>-6</sup> to 10<sup>-1</sup> W·cm<sup>-2</sup>·mA (approximately five orders of magnitude). In our study, the highest efficiency device operate in the p-n junction reverse bias avalanche mode and utilize current density increase by means of vertical and lateral electrical field confinement at a wedge-shaped n<sup>+</sup> tip placed in a region of lower doping density and opposite highly conductive p<sup>+</sup> regions.
    IEEE Photonics Technology Letters 01/2005; 17:2041-2043. · 2.04 Impact Factor
  • M. Plessis, H. Aharoni, L.W. Snyman
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    ABSTRACT: Low-voltage Si-LED operation can be achieved by fabricating devices with heavily doped n<sup>+</sup>p<sup>+</sup> junctions. Differences are observed between high-voltage avalanche and low-voltage field emission LED performance. The low-voltage devices exhibit a non-linear light intensity L vs. reverse current I relationship at low current levels, but a linear dependency at higher currents, compared to the linear behavior of avalanche devices at all current levels. Three regions of operation are identified for the low-voltage field emission LED's, namely L prop I<sup>3</sup> at low currents, L prop I<sup>2 </sup> at medium currents and eventually L prop I at higher currents. In the low-voltage non-linear region of operation, the shape of the emitted spectrum changes with reverse current. At low reverse current the field emission devices emit more long wavelength radiation than short wavelength radiation. As the reverse current increases, the short wavelength radiation increases relative to the long wavelength radiation, and at higher currents in the linear region of operation the ratio between long and short wavelength radiation remains constant
    Optoelectronic and Microelectronic Materials and Devices, 2004 Conference on; 01/2005
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    ABSTRACT: In this paper we report on the dependency of quantum efficiency of an avalanching light emitting junction on the current from an adjacent lying forward biased junction. The phenomenon is observed in a three terminal silicon CMOS bipolar junction light emitting device (Si CMOS BJT LED). Our observations show that the overall quantum efficiency and light emission from these type of devices can be improved to the N<sub>Q</sub>=10<sup>-4</sup> regime. The device has the potential of being fully integratable with any standard CMOS integrated circuitry with no adaptation to the CMOS design and processing procedures and light emissions can be confined to submicron dimensions. The optical emissions is about four orders higher than the low frequency detectivity for silicon CMOS detectors of comparable dimension. Our two junction, three terminal device also enable modulation of the light emission by a third terminal contact while using two terminals for biasing. The reverse bias avalanche configuration of the avalanching light emitting junction offers modulation capabilities of the device to within the GHz range.
    Electron Devices for Microwave and Optoelectronic Applications, 2004. EDMO 2004. 12th International Symposium on; 12/2004
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    ABSTRACT: Although silicon is an indirect bandgap material, light emission from reverse biased pn junctions has been observed. Although the quantum efficiency is low, it will be very advantageous to utilise these devices in all-silicon optoelectronic integrated circuits (OIC's). In this paper a review of our large area display and fibre-optic devices is given, followed by new research results achieved at CEFIM with regard to low voltage two-terminal line source Si LED's. A discussion of the differences observed between avalanche and field emission LED performance is presented. The detail spectral characteristics of field emission devices, and the spectral modulation of the optical signal from field emission light emitting devices are investigated. The design and simulation of a CMOS two-colour detector is presented, to be used as a detector for spectrally modulated optical signals. Gate-controlled diode MOS-like and carrier injection BJT-like multi-terminal devices are reviewed, and it is particularly indicated that both spatial modulation of the light emitting pattern and light intensity modulation can be achieved with these devices. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
    physica status solidi (a) 07/2004; 201(10):2225 - 2233. · 1.21 Impact Factor
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    ABSTRACT: A prototype Silicon CMOS Optical Integrated Circuit (Si CMOS OEIC) was designed and simulated using standard 0.8 micron Bi-CMOS silicon integrated circuit technology. The circuit consisted of an integrated silicon light emitting source, an optical wave-guiding structure, two integrated optical detectors and two high-gain CMOS transimpedance analogue amplifiers. Simulations with MicroSim PSpice software predict a utilizable bandwidth capability of up to 220 MHz for the trans-impedance amplifier for detected photo-currents at the input of the amplifier in the range of 1 nA to 100 nA and driving a 10mV to 1 V signal into a 100 kOmega load. First iteration OEIC structures were realised in 1.2 micron CMOS technology for various source-waveguide-detector arrangements. Current signal ranging from 1nA to 1 micro-amp was detected at detectors. The technology seems favorable for first-iteration implementation for digital communications on chip up to 200Mbps.
    Proc SPIE 07/2004;
  • H. Aharoni, M. du Plessis
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    ABSTRACT: A solution is presented for the fabrication of low-voltage, low-power (<4.25 V and <5 mW) silicon light-emitting devices (Si-LEDs), utilizing standard very large scale integration technology without any adaptation. Accordingly, they can be integrated with their signal processing CMOS and BiCMOS circuits on the same chip. This enables the fabrication of much needed all-silicon monolithic optoelectronic systems operated by a single supply. The structural details of two distinctly different line-patterned Si-LEDs are presented, composed of heavily doped n<sup>+</sup>p<sup>+</sup> junctions, made by BiCMOS n<sup>+</sup> sinker and PMOS p<sup>+</sup> source/drain doped regions, respectively. Using this approach, other Si-LED structures can be designed to yield low- or high-voltage Si-LED operation as well. Light is emitted at low reverse bias as a result of quantum transitions of carriers, generated by field emission, as indicated by the low reverse breakdown voltage V<sub>B</sub>, the soft "knee" I-V characteristics and the negative temperature coefficient of V<sub>B</sub>. The optical performance data show that, at low reverse operating current I<sub>R</sub>, the overall emitted light intensity L is a nonlinear function of I<sub>R</sub> and becomes linear at higher I<sub>R</sub>. A bell-shaped light spectrum is obtained, with an enhanced short wavelength and attenuated long-wavelength radiation, relative to that of avalanche Si-LEDs.
    IEEE Journal of Quantum Electronics 06/2004; · 1.83 Impact Factor
  • L.W. Snyman, H. Aharoni, M. du Plessis
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    ABSTRACT: A remarkable increase in the quantum efficiency and light emission intensity has been observed as a function of the current density for n<sup>+</sup>pp<sup>+</sup> silicon integrated light emitting devices which were fabricated with standard silicon CMOS technology. An increase of about two orders of magnitude for the quantum efficiency from 1.6 × 10<sup>-7</sup> to 5.8 × 10<sup>-6</sup> for current densities ranging from 1.6 × 10<sup>+2</sup> to 2.2 × 10<sup>+4</sup> A.cm<sup>-2</sup> is observed. The highest efficiency devices operate in the pn reverse breakdown avalanche breakdown mode and utilize current density increase by means of electrical field density confinement at a wedge shaped n<sup>+</sup> tip placed in a region of lower doping density opposite a highly conductive region. A best external quantum conversion efficiency of 5.8 × 10<sup>-6</sup> and light emission intensity of 0.1W per cm<sup>2</sup> were recorded at a current density level of 2.2 × 10<sup>+4</sup> at only 80 μm total current and 8V operating condition. This corresponds to a light intensity emission intensity of approximately 1nW in a 1 × 1 micron confined area on chip.
    Electron Devices for Microwave and Optoelectronic Applications, 2003. EDMO 2003. The 11th IEEE International Symposium on; 12/2003
  • Optical Engineering 01/2003; 42(10):3059-. · 0.88 Impact Factor
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    ABSTRACT: A prototype silicon CMOS optical integrated circuit (Si CMOS OEIC) was designed and simulated using standard 0.8 μm Bi-CMOS silicon integrated circuit technology. The circuit consisted of an integrated silicon light emitting source, an optical wave-guiding structure, two integrated optical detectors and two high-gain CMOS trans-impedance based analogue amplifiers. Simulations with MicroSim PSpice software predict a typical mean bandwidth capability of 185 MHz for the trans-impedance amplifier for detected photo-currents at the input of the amplifier in the range of 1 nA to 100 nA and driving a 10 kΩ load. First iteration waveguiding structures were realised in 1.2 μm CMOS technology for various source-waveguide-detector arrangements. Signal coupling ranging from 1 nA to 1 μA was detected at the detectors. The technology seems favourable for first-iteration implementations as diverse opto-electronic applications in silicon - CMOS integrated circuitry.
    Electron Devices for Microwave and Optoelectronic Applications, 2002. EDMO 2002. The 10th IEEE International Symposium on; 12/2002
  • M. du Plessis, H. Aharoni, L.W. Snyman
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    ABSTRACT: It is shown that, by using conventional VLSI design rules and device processing, a variety of two terminal and multiterminal integrated silicon light-emitting devices (Si-LEDs) can be routinely fabricated without any adaptation to the process, enabling the production of all-silicon monolithic optoelectronic systems. Their specific performance can be tailored by their different geometries and structures, yielding, by design, area, line, and point light-emitting patterns. The light-generating mechanisms are based on carrier quantum transitions in Si pn junctions, operated in the field emission or avalanche modes. Field emission Si-LEDs can operate at supply voltages compatible with those of integrated circuits (5 V or less). Avalanche Si-LEDs require higher operating voltages, but yield higher light intensities. The two terminal Si-LEDs yield a linear relation between the emitted light intensity and the driving current. The multiterminal Si-LEDs exhibit a nonlinear relation between the light emission intensity and the controlling electrical signal, enabling signal processing operations, which can not be attained in two terminal Si-LEDs. Two basic structures of multi terminal Si-LEDs are presented, i.e MOS-like structures, or carrier injection based structures (BJT-like devices). They possess different input impedances and both their emitted light intensities and emitting area patterns can be controlled by the input electrical signal.
    IEEE Journal of Selected Topics in Quantum Electronics 12/2002; · 4.08 Impact Factor
  • Monuko du Plessis, Herzl Aharoni
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    ABSTRACT: Multi-terminal silicon CMOS light emitting diode structures are described where the light emission intensity from the reverse biased pn junctions is modulated by gate voltages applied to overlapping polysilicon gates. Linear arrays, as well as two-dimensional arrays of Si LED's were realized in combination with a grid of overlapping resistive polysilicon gates. The gate voltages applied to the resistive gate grid at different points modulated the pn junction breakdown, and thus the reverse avalanche current through the diodes. A novel structure where the light pattern can be changed from two point sources to a single line source using one MOS control gate has also been realized. A linear relationship exists between reverse current and light intensity, but due to the nonlinear variation of breakdown voltage with applied MOS gate voltage, the light intensity varies approximately with the square root of the applied voltage. This nonlinear behavior may facilitate electro-optical signal processing. The resistive gate grid voltages can be used to generate different breakdown voltages at different positions in the LED array. The result is that the array emission pattern is a function of the applied gate voltages. Spatial modulation of the light emission pattern is demonstrated for several device structures.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
    03/2002;
  • Monuko du Plessis, Herzl Aharoni
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    ABSTRACT: Multi-terminal silicon CMOS light emitting diode structures are described where the light emission intensity from the reverse biased pn junctions is modulated by gate voltages applied to overlapping polysilicon gates. Linear arrays, as well as two-dimensional arrays of Si LED's were realized in combination with a grid of overlapping resistive polysilicon gates. The gate voltages applied to the resistive gate grid at different points modulated the pn junction breakdown, and thus the reverse avalanche current through the diodes. A novel structure where the light pattern can be changed from two point sources to a single line source using one MOS control gate has also been realized. A linear relationship exists between reverse current and light intensity, but due to the nonlinear variation of breakdown voltage with applied MOS gate voltage, the light intensity varies approximately with the square root of the applied voltage. This nonlinear behavior may facilitate electro-optical signal processing. The resistive gate grid voltages can be used to generate different breakdown voltages at different positions in the LED array. The result is that the array emission pattern is a function of the applied gate voltages. Spatial modulation of the light emission pattern is demonstrated for several device structures.
    Proc SPIE 03/2002;
  • M. du Plessis, H. Aharoni, L.W. Snyman
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    ABSTRACT: Photon emission from reverse biased silicon pn junctions was reported for the first time in 1955. However, Si-LED's will only find applications if they can be fully integrated with standard silicon integrated circuits, and several attempts have been made in this regard. This paper discusses the characteristics and design of silicon light emitting devices in standard CMOS technology with no process modifications
    Semiconductor Conference, 2001. CAS 2001 Proceedings. International; 02/2001
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    ABSTRACT: Three structures of silicon light emitting sources are described, each presenting higher electrical-to-optical conversion efficiency. The advantage of these structures lay in the fact that they were all fabricated using conventional standard VLSI technology, without any alternation of the processing procedure
    Lasers and Electro-Optics, 2001. CLEO/Pacific Rim 2001. The 4th Pacific Rim Conference on; 02/2001

Publication Stats

156 Citations
22.85 Total Impact Points

Institutions

  • 1996–2007
    • Ben-Gurion University of the Negev
      • Department of Electrical and Computer Engineering
      Beersheba, Southern District, Israel
  • 2004–2005
    • Tshwane University of Technology
      • Department of Electrical Engineering
      Pretoria, Gauteng, South Africa
  • 1999–2005
    • University of Pretoria
      • Department of Electrical, Electronic and Computer Engineering
      Pretoria, Gauteng, South Africa