The role of extended and point defects, and key impurities such as C, O, and H, on the electrical and optical properties of GaN is reviewed. Recent progress in the development of high reliability contacts, thermal processing, dry and wet etching techniques, implantation doping and isolation, and gate insulator technology is detailed. Finally, the performance of GaN-based electronic and photonic devices such as field effect transistors, UV detectors, laser diodes, and light-emitting diodes is covered, along with the influence of process-induced or grown-in defects and impurities on the device physics.

Gan : processing, defects, and devices

Optofluidics - the synergistic integration of photonics and microfluidics - has recently emerged as a new analytical field that provides a number of unique characteristics for enhanced sensing performance and simplification of microsystems. In this review, we describe various optofluidic architectures developed in the past five years, emphasize the mechanisms by which optofluidics enhances bio/chemical analysis capabilities, including sensing and the precise control of biological micro/nanoparticles, and envision new research directions to which optofluidics leads.

/pdf/optofluidic-microsystems-for-chemical-and-biological-2x1od0syk0.pdf

Optofluidic microsystems for chemical and biological analysis

The coloniality of power is understood by Anibal Quijano as at the constituting crux of the global capitalist system of power. What is characteristic of global, Eurocentered, capitalist power is that it is organized around two axes that Quijano terms “the coloniality of power” and “modernity.” The coloniality of power introduces the basic and universal social classification of the population of the planet in terms of the idea of race, a replacing of relations of superiority and inferiority established through domination with naturalized understandings of inferiority and superiority. In this essay, Lugones introduces a systemic understanding of gender constituted by colonial/modernity in terms of multiple relations of power. This gender system has a light and a dark side that depict relations, and beings in relation as deeply different and thus as calling for very different patterns of violent abuse. Lugones argues that gender itself is a colonial introduction, a violent introduction consistently and contemporarily used to destroy peoples, cosmologies, and communities as the building ground of the “civilized” West.

Heterosexualism and the Colonial / Modern Gender System

We review the family of optoelectronic devices whose performance is enhanced by placing the active device structure inside a Fabry‐Perot resonantmicrocavity. Such resonantcavity enhanced (RCE) devices benefit from the wavelength selectivity and the large increase of the resonant optical field introduced by the cavity. The increased optical field allows RCE photodetector structures to be thinner and therefore faster, while simultaneously increasing the quantum efficiency at the resonant wavelengths. Off‐resonance wavelengths are rejected by the cavity making RCE photodetectors promising for low crosstalk wavelength division multiplexing(WDM) applications. RCE optical modulators require fewer quantum wells so are capable of reduced voltage operation. The spontaneous emission spectrum of RCE light emitting diodes(LED) is drastically altered, improving the spectral purity and directivity. RCE devices are also highly suitable for integrated detectors and emitters with applications as in optical logic and in communication networks. This review attempts an encyclopedic overview of RCE photonicdevices and systems. Considerable attention is devoted to the theoretical formulation and calculation of important RCE device parameters. Materials criteria are outlined and the suitability of common heteroepitaxial systems for RCE devices is examined. Arguments for the improved bandwidth in RCE detectors are presented intuitively, and results from advanced numerical simulations confirming the simple model are provided. An overview of experimental results on discrete RCE photodiodes, phototransistors, modulators, and LEDs is given. Work aimed at integrated RCE devices,optical logic and WDM systems is also covered. We conclude by speculating what remains to be accomplished to implement a practical RCE WDM system.

Resonant cavity enhanced photonic devices

(2004). The Color of Supremacy: Beyond the discourse of ‘white privilege’. Educational Philosophy and Theory: Vol. 36, No. 2, pp. 137-152.

The Color of Supremacy: Beyond the discourse of ‘white privilege’

Index-guided vertical cavity top-surface emitting laser diodes have been fabricated from an all epitaxial structure with conducting mirrors by selective lateral oxidation of AlGaAs At low voltage, a 78% slope efficiency, and a 350 mu A threshold current in a single device combine to yield a maximum power conversion efficiency of 50% at less than a 2 mA drive current The device operates in a single mode up to 15 mW >

/pdf/selectively-oxidised-vertical-cavity-surface-emitting-lasers-n7kjxyn3ih.pdf

Selectively oxidised vertical cavity surface emitting lasers with 50% power conversion efficiency

Novel vertical-cavity surface emitting lasers fabricated using selective oxidation to form a current aperture under a top monolithic distributed Bragg reflector mirror are reported. Large cross-sectional area lasers (259 µm2) exhibit threshold current densities of 150 A/cm2 per quantum well and record low threshold voltage of 1.33 V. Smaller lasers (36 µm2) possess threshold currents of 900 µA with maximum output powers greater than 1 mW. The record performance of these oxidised vertical-cavity lasers arises from the low mirror series resistance and very efficient current injection into the active region.

/pdf/low-threshold-voltage-vertical-cavity-lasers-fabricated-by-552njsol0q.pdf

Low threshold voltage vertical-cavity lasers fabricated by selective oxidation

We show that the partitioning of power into the two orthogonal eigen polarizations of infra-red gain-guided vertical cavity lasers depends upon the relative spectral overlap of the nondegenerate polarization cavity resonances with the laser gain spectrum. Furthermore, at the condition where the polarization resonances and the peak laser gain are aligned, abrupt switching of power between the eigen polarizations is observed as the gain sweeps through the polarization resonances. The gain-dependence of the polarization requires spectral splitting between the eigen polarizations, which is found to be strongly influenced by local strain. The polarization of the fundamental and higher-order spatial modes can be selected and maintained for all InGaAs vertical-cavity lasers in a wafer simply by employing a 20 nm or greater blue-shift offset of the peak laser gain relative to the cavity resonances. >

/pdf/gain-dependent-polarization-properties-of-vertical-cavity-54l438mz2g.pdf

Gain-dependent polarization properties of vertical-cavity lasers

A semiconductor light-emitting device and method. The semiconductor light-emitting device is provided with at least one control layer or control region which includes an annular oxidized portion thereof to channel an injection current into the active region, and to provide a lateral refractive index profile for index guiding the light generated within the device. A periodic composition grading of at least one of the mirror stacks in the device provides a reduced operating voltage of the device. The semiconductor light-emitting device has a high efficiency for light generation, and may be formed either as a resonant-cavity light-emitting diode (RCLED) or as a vertical-cavity surface-emitting laser (VCSEL).

Efficient semiconductor light-emitting device and method

This paper discusses the issues involving the design and fabrication of vertical-cavity surface-emitting lasers (VCSELs). A review of the basic experimental structures is given, with emphasis on recent developments in distributed Bragg reflectors, gain media, as well as current and optical confinement techniques. The paper describes present VCSEL performance, in particular, those involving selective oxidation and visible wavelength operation.

/pdf/design-fabrication-and-performance-of-infrared-and-visible-ivy2lksajg.pdf

Kevin L. Lear

Papers

Selectively oxidised vertical cavity surface emitting lasers with 50% power conversion efficiency

Low threshold voltage vertical-cavity lasers fabricated by selective oxidation

Gain-dependent polarization properties of vertical-cavity lasers

Efficient semiconductor light-emitting device and method

Design, fabrication, and performance of infrared and visible vertical-cavity surface-emitting lasers