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Bogalecki A.W.,INSiAVA Pty Ltd. | Du Plessis M.,University of Pretoria | Venter P.J.,University of Pretoria | Nell I.J.,University of Pretoria | Goosen M.E.,INSiAVA Pty Ltd.
Proceedings of the International Conference on Microelectronics, ICM | Year: 2010

The directionality and external optical power of CMOS light sources was improved a factor 3.9 by implementing integrated light reflectors in an unmodified CMOS process. Implementing such reflectors successfully demonstrated a CMOS micro-display and a 350 MHz Si optical communication link. © 2009 IEEE.


Du Plessis M.,University of Pretoria | Venter P.J.,University of Pretoria | Bogalecki A.W.,INSiAVA Pty Ltd.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010

For CMOS silicon-based light emitting devices to become practical the external power efficiency must be increased. In this paper a reach-through technique is described whereby the external power efficiency can be increased as a result of three phenomena: i) increase in internal quantum efficiency, ii) increase in light extraction efficiency, and iii) lower operating voltage. The three techniques are discussed and the factor 7 improvement in external power efficiency will be described in terms of the electrical characteristics as well as the external radiation patterns. © 2010 Copyright SPIE - The International Society for Optical Engineering.


Bogalecki A.W.,INSiAVA Pty Ltd. | Du Plessis M.,University of Pretoria
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010

To investigate quantum-confinement (QC) effects on silicon (Si) light source electroluminescence (EL) properties like external power efficiency (EPE) and spectral emission, nanometer-scale Si finger junctions were manufactured in a fully customized silicon-on-insulator (SOI) production technology. All spectrometer-measured thickness-confined SOI light sources displayed pronounced optical power for 600 nm < λ < 1 μm. The best thickness-confined SOI light source emitted about 24 times more optical power around λ = 844 nm and exhibited an EPE improvement factor of about 21 compared to a 350 nm bulk-CMOS avalanche reference light-source operating at the same current. Internal quantum efficiency (IQE) enhancements factors of about 3.5 were attributed to carrier-confinement. The punch-through (PT) technique, which introduced breakdown voltages as low as 6 V, increased the SOI light source EPE by about a factor 2.5. It was estimated that geometric-optical improvement techniques that include Si finger surface profiling, raised the SOI light source external quantum efficiency (EQE) by about a factor 1.7. It was further shown that the SOI Si handle could be used to reflect up to about 40 % of light that would otherwise be lost due to downward radiation back up, thereby increasing the EPE of SOI light sources. © 2010 Copyright SPIE - The International Society for Optical Engineering.


Plessis M.d.,University of Pretoria | Rademeyer P.,InSiAva Pty Ltd.
Solid-State Electronics | Year: 2010

In this paper a novel technique to analyze the low-voltage breakdown regime of silicon diodes is presented. It is shown that the field emission tunnel current component of the reverse current does not cause energy transitions of carriers, and therefore will not emit photons. All photons being emitted from the pn junction are due to avalanche electroluminescence as a result of hot carrier energy relaxation processes. Measuring the light intensity output as a function of reverse current, the two current components (field emission and impact ionization) can be extracted as a function of reverse voltage. The experimental results were verified using the differential dynamic impedance method, as well as fitting a theoretical model to the extracted tunnel current. The temperature coefficient of current also indicated the transition from tunneling to avalanche. © 2010 Elsevier Ltd. All rights reserved.


Venter P.J.,University of Pretoria | Du Plessis M.,University of Pretoria | Bogalecki A.W.,INSiAVA Pty Ltd. | Van Rensburg C.J.,INSiAVA Pty Ltd.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

Silicon-on-insulator (SOI) is becoming an important technology platform in nanometer scale CMOS integrated circuits. The platform offers a number of distinct advantages over bulk CMOS for materializing silicon light sources based on hot carrier luminescence. This work describes the design of nanoscale silicon structures for enhanced light emission with improved power efficiency, which allows the use of SOI light sources in short-haul optical communication links with extended possibilities for other applications. It has been shown experimentally that reducing the dimensions of the active material results in an improvement of electroluminescent power emitted from forward-biased pn-junctions. Previously published results show a similar trend for light sources based on hot carrier luminescence. Building on our previous work in SOI light sources, multiple fingerlike junctions are manufactured in an arrayed fashion for coupling into large diameter core optical fibers for CMOS optical communications up to a few hundred meters. The manufacturing methodology and associated challenges are discussed for the scaling down of device dimensions, and difficulties in realizing the structures are investigated. The optical power characteristics are discussed as well as the spectral nature of emission along with the advantages and disadvantages thereof. This work compares different architectures of light sources that were implemented where a comparison is drawn between previous SOI devices as well as bulk CMOS. We believe the improved SOI light sources are fully compatible with modern CMOS technologies based on SOI and may provide such technologies with a much needed light source as part of the circuit designer's toolkit. © 2013 SPIE.


Patent
Insiava Pty Ltd | Date: 2013-12-18

A light emitting device (10) comprises a first body (12) of an indirect bandgap semiconductor material. A junction region (118) in the body is formed between a first region (112.1) of the body of a first doping kind and a second region (112.2) of the body of a second doping kind. A terminal arrangement is connected to the first and second regions of the body for, in use, reverse biasing the junction region into avalanche or field emission mode to inject carriers into the first junction region. A second body (122) of an isolation material is located immediately adjacent at least two of a top wall, a bottom wall, and sidewalls of the first region, thereby to reduce parasitic injection from the first region.


Patent
INSIAVA PTY Ltd | Date: 2011-01-21

A light emitting device (10) comprises a body (11) comprising a substrate (12) of a p-type semiconductor material. The substrate has an upper surface (14) and having formed therein on one side of the upper surface and according to a bulk semi-conductor fabrication process utilizing lateral active area isolation techniques: a first n+-type island (16) to form a first junction (24) between the first island and the substrate; and a second n+-type island (18) spaced laterally from the first island (16). The substrate provides a laterally extending link (20) between the islands having an upper surface. The upper surface of the link, an upper surface of the island (16) and an upper surface of the island (18) collectively form a planar interface (21) between the body (11) and an isolation layer (19) of the device. The device comprises a terminal arrangement to apply a reverse bias to the first junction, to cause the device to emit light. The device is configured to facilitate the transmission of the emitted light.


Patent
INSIAVA PTY Ltd | Date: 2012-09-12

A light emitting device (10) comprises a body (12) of a semiconductor material having a first face (14) and at least one other face (16). At least one pn-junction (18) in the body is located towards the first face and is configured to be driven via contacts on the body into a light emitting mode. The other face (16) of the body is configured to transmit from the body light emitted by the at least one pn-junction (18) in the near infrared part of the spectrum and having wavelengths longer than 1 m.


Patent
Insiava PTY Ltd | Date: 2011-07-08

A micro optical device 10 comprises a body 12. The body comprises a movable member 14, which is moveable relative to another part 26 of the body. An optical element, such as an optical source 16, is provided on or within the movable member. The moveable member may be subjected to a parameter, such as mass, to be sensed and by monitoring at detector 22 changes of an optical signal emitted by the optical source, the parameter may be monitored.


An optoelectronic device comprises a body of an indirect bandgap semiconductor material having a surface and a photon active region on one side of the surface. A light directing arrangement is formed integrally with the body on an opposite side of the surface.

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