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Journal ArticleDOI

Photoluminescence measurement system using fiber optics

01 Feb 1990-Review of Scientific Instruments (American Institute of Physics)-Vol. 61, Iss: 2, pp 756-759

AbstractWe describe a novel photoluminescence measurement apparatus which incorporates an optical fiber for carrying both the excitation beam and the luminescence from the sample. The advantages of the optical fiber makes the system very versatile and suitable for sensitive measurements. The collection efficiency of the setup is demonstrated to be the same as that of a conventional setup. Several photoluminescence spectra of III‐V compounds recorded using the apparatus are also included to demonstrate its applicability over a wide wavelength range (0.8–2.0 μm).

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Citations
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Journal ArticleDOI
Abstract: Low-repetition-rate pulsed lasers are excellent sources for two-photon excitation of samples frozen in low-temperature glassy solvents. Unfortunately, similar efforts to combine synchronously-pumped dye laser excitation with normal cryostats and sample cells have consistently failed. The continuous nature of the laser creates a weak refractive index gradient which causes the beam to wander randomly in space. We have found that a fiber-optic probe directly frozen in the glassy sample permits two-photon excited fluorescence spectra to be obtained. This arrangement is stable because the fiber restricts beam-induced refractive index changes to harmless expansion. Studies of fluxional fluorophores indicate that the viscosity at the fiber tip is not significantly changed under conditions of average power known to cause beam wander in ordinary cryostat cells.

2 citations

01 Jan 2015
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.

1 citations


Cites background from "Photoluminescence measurement syste..."

  • ...It was reported that some research used a micro fiber instead of a microscope to focus the excitation beam on samples[7, 22]....

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DissertationDOI
01 Jan 2019
Abstract: This thesis presents a novel method to quantify the localised carrier collection efficiency of thin film solar cells by integrating a theoretical model with data from a newly developed combined measurement system capable of measuring spectrally-resolved photoluminescence (PL), time-resolved photoluminescence (TRPL) and transient photocurrent decay (TPCD) at the same spot on the solar cell. This combined measurement approach allows for the identification and further understanding of the limiting factors in the carrier collection efficiency of solar cells. [Continues.]

References
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Journal ArticleDOI
Abstract: Photoluminescence provides a non-destructive technique for the analysis of semiconductors. The method provides information both on intrinsic and extrinsic semiconductors properties. This article reviews application to extrinsic effects induced by impurities or lattice defects. The method is shown to be particularly suitable for the centres responsible for the shallow donor and acceptor species by which the electrical properties are usually controlled, as well as all forms of explicit luminescence activator. It can also be applied to certain deep states, provided that carrier exchange with these centres does not involve so much local lattice relaxation that the associated transitions become entirely non-radiative. Even when this is so, transition metals may still be detected through internal electronic relaxations within a given charge state, at least the final step of which is frequently radiative. In all cases, measurements at low cryogenic temperatures are required to obtain the fullest spectroscopic information usually necessary to characterise a given type of transition and to discriminate between species within a given class. The honor and acceptor-related recombinations may be of bound exciton, donor acceptor pair or free to bound type, and equivalent processes may be seen for other types of centre. These topics are treated in separate sections of the review, following an introduction which includes general remarks about equipment and application of the technique. Examples are taken from the most technologically important semiconductor systems. Compared with the usual elementary techniques of electrical characterisation, photoluminescence has advantages of generally easy discrimination between species and can provide simultaneous information on many types of centre. However, it is comparatively less well suited to the determination of impurity concentration, particularly for the electrical majority species. Techniques whereby concentration information may be obtained for various types of species are briefly described. The review ends with a subsection devoted to topographic techniques involving photoluminescence, or the closely-related cathodoluminescence and junction electroluminescence, which can reveal information on totally non-radiative extended defects as well as on spatial distributions of radiative species.

92 citations

Journal ArticleDOI
Abstract: We describe a novel light collection system for cathodoluminescence scanning electron microscopy. Cathodoluminescence emitted from the sample surface enters directly into the facet of an optical fiber, which is held less than a millimeter away from the sample to optimize the collection efficiency. The fiber is small enough that it has a minimal effect on access to the sample by other detection apparatus. Three axis positioning of the fiber is accomplished with motorized translation stages located in the sample chamber. Techniques for generating cathodoluminescence images and local spectra are discussed. The techniques are applied to oval defects in molecular beam epitaxially grown GaAs/AlGaAs epilayers, and the results are presented.

21 citations

Journal ArticleDOI
Abstract: An optical‐fiber‐based apparatus for measuring photoluminescence spectra has been demonstrated. The use of a variable ratio fiber directional coupler and an integral fiber microlens greatly simplifies the optical system for both photoluminescence excitation and collection and permits the attainment of high output power densities (40 kW/cm2) for modest fiber input powers (<5 mW). Spectra from several III‐V semiconductor samples are shown which illustrate the sensitivity of the apparatus.

2 citations