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Pretoria, South Africa

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.


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

A light emitting device (


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

A micro optical device

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