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Setup for Micro Photo- and Electro-Luminescence of Optoelectronic Device Structures

01 Jan 2015-
TL;DR: In this article, a Czerny Turner diffraction grating based monochromator is used to measure photoluminescence (PL) emission induced by photon absorption in a material where electrons are excited from the ground state to excited states, then relax to the lowest excited states.
Abstract: Photoluminescence (PL) is an optical emission induced by photon absorption in a material where electrons are excited from the ground state to excited states, then relax to the lowest excited states and recombine radiatively. The PL emission provides vital information on bandgap energy, material purity and crystal quality. In this project, a PL characterization system, also capable of electroluminescence (EL) measurements, was designed and assem- bled to measure optoelectronic device structures with the capabilities of recording PL or EL spectra as well as micrometer-resolved PL or EL maps on device structures or active components.In order to realize the system with the above functions, an optical setup and a monochro- mator were used to achieve micrometer-range resolution and reasonable signal-to-noise ra- tio. A hardware control platform needed to be designed and assembled to control the precise movement of the sample stage and monochromator as well as for acquiring the signal. A PC-based control software were developed for fully automatic measurements . Furthermore, adequate alignment and calibration methods had to be developed to tune the optical path, monochromator and control program.The setup employs the basic ideas of confocal microscopy, with the parallel laser input focused on the sample surface with a spot diameter of 0.78 μm. A Czerny Turner diffraction grating based monochromator is used to measure PL emissions. A 532 nm laser diode and an InGaAs or Si detector are applied in the system for spectral range of detection of at least 850- 1600 nm, i.e. covering the important data and tele communication bands. The project builds on a platform containing EasyDrivers, an Anduino Uno micro-controller and a Labview based operation software, together working with an amplifier circuit for stepper motors actuation and signal acquisition. Finally, different quantum well samples were measured, showing that the wavelength accuracy and resolution as well as the program flexibility meet the specifications of the setup.
Citations
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Patent
07 Jun 2018
TL;DR: In this article, the condition of photovoltaic modules at one or more points in time was determined using line-scanning luminescence imaging techniques, including the detection of defects that may cause or may have caused module failure.
Abstract: Some examples include determining the condition of photovoltaic modules at one or more points in time, in particular using line-scanning luminescence imaging techniques. One or more photoluminescence and/or electroluminescence images of a module may be acquired and processed using one or more algorithms to provide module data, including the detection of defects that may cause or may have caused module failure. Additionally, some examples include determining the condition of photovoltaic modules, such as throughout the production, transport, installation and service life of the photovoltaic modules.

6 citations

References
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Journal ArticleDOI
TL;DR: It is found that confocal imaging gives greatly enhanced images of biological structures viewed with epifluorescence, and the improvements are such that it is possible to optically section thick specimens with little degradation in the image quality of interior sections.
Abstract: Scanning confocal microscopes offer improved rejection of out-of-focus noise and greater resolution than conventional imaging. In such a microscope, the imaging and condenser lenses are identical and confocal. These two lenses are replaced by a single lens when epi-illumination is used, making confocal imaging particularly applicable to incident light microscopy. We describe the results we have obtained with a confocal system in which scanning is performed by moving the light beam, rather than the stage. This system is considerably faster than the scanned stage microscope and is easy to use. We have found that confocal imaging gives greatly enhanced images of biological structures viewed with epifluorescence. The improvements are such that it is possible to optically section thick specimens with little degradation in the image quality of interior sections.

884 citations


"Setup for Micro Photo- and Electro-..." refers background in this paper

  • ...Thus the core design of a confocal microscope, employment of confocal setup of entrance and exist pinholes, successfully prevents the out-of-focus light from reaching the detector and consequently improves both in lateral and axial resolutions[23, 24]....

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Journal ArticleDOI
TL;DR: In this paper, various models for calculation of physical parameters in compound alloys are discussed and the results for In1−x Gax Asy P1−y quaternaries are presented.
Abstract: Various models for calculation of physical parameters in compound alloys are discussed and the results for In1−x Gax Asy P1−y quaternaries are presented. The model used is based on a linear interpolation scheme, and therefore necessitates known values of the parameters for the related binary and ternary alloys. The material parameters considered in the present study can be classified into the following eleven groups: (1) lattice constant and crystal density, (2) thermal expansion coefficient, (3) electronic‐band structure, (4) external perturbation effect on the lowest‐direct gap, (5) effective mass, (6) dielectric constant, (7) Frohlich coupling parameter, (8) elastic properties, (9) piezoelectric properties, (10) deformation potential, and (11) excitonic effect. Of particular interest is the deviation of material parameters from linearity with respect to the alloy composition. It is found that the present model provides generally acceptable parameters, in good agreement with the existing experimental da...

686 citations


"Setup for Micro Photo- and Electro-..." refers methods in this paper

  • ...According to the linear interpolation by Sadao Adachi[44], the energy offset by the heavy and light hole split of measurement in Fig 6....

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Journal ArticleDOI
TL;DR: In this paper, the Peierls stress is used to explain the elastic strains present in films of germanium on gallium asrenide and explain the reduction of these strains by a high temperature anneal.
Abstract: Misfit dislocations are often transported to the interface between crystals by glide. In materials with the diamond or sphalerite structures, glide is inhibited by the Peierls stress. The aim of this paper is to present a theory for misfit accommodation which includes the effect of the Peierls stress. It is used to explain the elastic strains present in films of germanium on gallium asrenide and to explain the reduction of these strains by a high‐temperature anneal. The strains in germanium on gallium arsenide, and the effect of temperature upon them, are not explained by earlier theories for the accommodation of misfit between one crystal and another.

563 citations


"Setup for Micro Photo- and Electro-..." refers methods in this paper

  • ...According to Mathews-Blakeslee theory[8], misfit dislocations are generated when structure thickness beyond critical layer thickness hc....

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Book
01 Jan 2000
TL;DR: Semiconductors and heterostructures solutions Schrodinger's equation numerical solutions diffusion impurities excitons quantum wires and dots carrier scattering empirical pseudopotential theory microscopic electronic properties of heterostructure application to quantum wires.
Abstract: Semiconductors and heterostructures solutions Schrodinger's equation numerical solutions diffusion impurities excitons quantum wires and dots carrier scattering empirical pseudopotential theory microscopic electronic properties of heterostructures application to quantum wires and dots. Appendices: computer codes used in chapters 2-11 computer code summary materials paramters.

542 citations


"Setup for Micro Photo- and Electro-..." refers background in this paper

  • ...The remaining steps of one stepper motor (which is defined by "command[2]") are found according to the basic...

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Journal ArticleDOI
Eugene A. Fitzgerald1
TL;DR: In this paper, an historical perspective of theoretical work and some early experimental work in the field of dislocations in strained-layer epitaxy is presented in a didactic fashion.

516 citations


"Setup for Micro Photo- and Electro-..." refers background in this paper

  • ...Device Structures YUXUAN SUN Master of Science Thesis Stockholm, Sweden 2015 TRITA-ICT-EX-2015:136 The cover image shows a high-resolution photoluminescence microscopy image revealing a network of misfit dislocations in a partly relaxed InGaAs/GaAs interface....

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  • ...The optical property of QW can be degraded depending on the dislocation density, which comes from the increasing number of non-radiative recombination centers in the vicnity of the dislocations.[9] A visible confirmation of the degraded PL result is the dark lines appearing in spatial resolved (mapping)...

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  • ...A typical example is the epitaxy semiconductor of InGaAs/GaAs[1, 9, 10]....

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