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1
AMMONO-GaN substrates for microwave and RF electronics applications
Dwiliński R., Doradziński R., Sierzputowski L., Kucharski R., Zając M.
Elektronika : konstrukcje, technologie, zastosowania
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2012
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Vol. 53, nr 7
11-13
EN
Bulk GaN crystals are regarded as the most promising candidates for substrates for optoelectronic, high power and high frequency electronic devices. In this paper some principles of ammonothermal method of bulk gallium nitride growth are presented. Excellent structural properties and wide spectrum of electrical parameters of obtained this way truły bulk GaN crystals are shown. In considered crystals a Iow dislocation dens ity (5x10³ cm²) is attainable. High crystallinity is manifested by extremely fiat crystal lattice and very narrow (FWHM=16 arcsec) X-ray rocking. Both polar and nonpolar ammonothermal GaN substrates enabled to grow high quality, strain-free homoepitaxial layers and AlGaN/GaN heterostructures. This may enable a breakthrough in manufacturing of aforementioned high power electronic devices.
PL
Objętościowe kryształy GaN uważane są za najbardziej obiecujące materiały do zastosowań w produkcji przyrządów optoelektronicznych i elektronicznych wysokiej mocy i wysokiej częstości. W tym artykule przedstawiony zostanie ogólny zarys metody amonotermalnej wzrostu objętościowego GaN. Doskonałe własności strukturalne i szerokie spektrum własności elektrycznych otrzymywanych tą metodą kryształów zostaną zaprezentowane. W rozważanych kryształach bardzo niska gęstość dyslokacji (5x10³ cm²) jest osiągana. Wysoka jakość strukturalna objawia się bardzo płaską siecią krystaliczną, jak również niską szerokością krzywej odbić promieniowania X (FWHM=16 arcsec). Zarówno polarne, jak i niepolarne podłoża AMMONO-GaN umożliwiają wzrost wysokiej jakości, nienaprężo nych warstw homoepitaksjalnych i heterostruktur AlGaN/GaN, co może spowodować przełom w produkcji wspomnianych wyżej przyrządów elektronicznych wysokiej mocy.
2
Fotoniczne układy scalone
Ławniczuk K., Piramidowicz R., Szczepański P., Smit M. K., Leijtens X. J. M.
Elektronika : konstrukcje, technologie, zastosowania
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2011
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Vol. 52, nr 2
74-80
PL
W artykule omówiono rozwój fotonicznych układów zintegrowanych oraz techniki integracji optycznych komponentów na podłożach półprzewodnikowych z fosforku indu. Przedstawiono postęp i rozwój w fotonice oraz obowiązujące tu prawo Moore'a. Prezentowano także koncepcję technologii generycznej oraz podstawowe bloki funkcjonalne fotoniki wykorzystywane do projektowania oraz wytwarzania urządzeń fotonicznych. Omówiono europejską platformę fotoniczną Jeppix służącą do projektowania układów scalonych i sposób jej funkcjonowania. Opisana została również zasada działania podstawowych komponentów optycznych oraz przedstawiono kilka zaawansowanych funkcjonalnie fotonicznych układów scalonych.
EN
In this paper a brief look on development of photonic integrated circuits and current status of integration technologies based on indium phosphide platform is given. Progress in photonics and corresponding Moore's law are described. Generic technology concept and basic building blocks which are used to design and fabricate functionally advanced photonic devices are presented. Model of multi-project wafer run and Jeppix, the European photonic platform, are described. An account of the operation principle of optical components is given and few examples of complex photonic circuits are shown.
3
Content available remote Photoreflectance study of partially relaxed epitaxial InGaAs on GaAs
Motyka M., Gelczuk Ł., Dąbrowska-Szata M., Serafinczuk J., Kudrawiec R., Misiewicz J.
Optica Applicata
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2009
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Vol. 39, nr 3
561-570
EN
Room temperature photoreflectance (PR) spectroscopy and high resolution X-ray diffraction (HRXRD) have been used to investigate InxGa1-xAs layers grown compressively by MOVPE on GaAs substrates, with different composition and thickness. HRXRD reveals that all the samples are partially relaxed and In composition has been determined for each of the samples. The effects of residual strain on the optical response of the samples, namely interband transitions and the valence band splitting, were analyzed by fitting the standard line shape form to the PR data. The energies determined experimentally as a function of indium content were compared to those obtained in the framework of the elastic strain theory for pseudomorphic layers. This comparison allows us to estimate the extent of strain relaxation and to determine the residual strain values in the samples. Furthermore, we revealed that the measured residual strain ?res follows t-1/2 dependence on the epitaxial layers thickness t. This confirms the appropriateness of the nonequilibrium models (energy-balance models) for these structures.
4
Content available remote Dependence of GaAs and Si surface energy on the misorientation angle of crystal planes
Zdyb A., Olchowik J. M., Mucha M.
Materials Science Poland
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2006
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Vol. 24, No. 4
1109--1114
EN
The paper reports on the dependence of Si and GaAs surface energies on the misorientation angle of Si and GaAs crystal planes in a broad angle range. The energetic balance between GaAs and Si is unfavourable for growth of GaAs on Si substrate. Minima of the surface energy correspond to GaAs/Si heterostructure interface energy minima which indicate preferable crystal orientations for obtaining GaAs layers on Si.
5
Content available remote Resonant cavity enhanced photonic devices.
Bugajski M., Muszalski J., Mroziewicz B., Regiński K., Ochalski T.J.
Optica Applicata
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2001
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Vol. 31, nr 2
273-288
EN
We review our recent works on technology, basic physics and applications of one-dimensional photonic structures. We demonstrate spontaneous emission control in In/sub x/Ga/sub 1-x/As/GaAs planar microcavities with DBR reflectors. The room temperature emission in lambda -sized cavities is enhanced in comparison with its free space value, while in lambda /2-sized cavities suppression of spontaneous emission is observed. The characteristics of spontaneous emission in microcavities depend on the wavelength difference between the emitter and the cavity resonance. It has been shown that ideal tuning of the cavity can be achieved by adjusting sample temperature. In general, observed trends are in agreement with theoretical predictions. These changes to the spontaneous emission process directly affect vertical-cavity laser (VCSEL) properties. An increased coupling efficiency of spontaneous emission into the lasing mode is observed in VCSELs with lambda -sized cavities. We demonstrate the operation of resonant-cavity light emitting diodes (RC LED) and optically pumped VCSELs developed recently at the Department of Physics and Technology of Low Dimensional Structures of the Institute of Electron Technology. The epitaxial growth issues, fabrication technology and basic characteristics of these devices are discussed
6
Content available remote Operation of arsenide diode lasers at elevated temperatures
Czyszanowski T.
Optica Applicata
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2001
|
Vol. 31, nr 2
301-311
EN
Some design modification and optimisation of the GaAs/(AlGa)As separate-confinement-heterostructure (SCH) as well as the graded-index separate-confinement-heterostructure (GRIN-SCH) semiconductor lasers are discussed to reduce their threshold concentrations at elevated temperatures. A detailed optical model of arsenide lasers is used to compare an impact of some structural details on lasing thresholds at various temperatures. In the analysis, both optical gain and losses are modelled rigorously. It has been demonstrated that operation of the arsenide lasers considered is not changing dramatically at elevated temperatures not exceeding 400 K.
7
Content available remote Modelling of radial steam oxidation of AlAs layers in cylindrically symmetric mesa structures of vertical-cavity surface-emitting lasers
Nakwaski W., Maćkowiak P.
Optica Applicata
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2001
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Vol. 31, nr 2
289-299
EN
During the last several years selective steam oxidation process has evolved into a key technology in fabrication of high-performance vertical-cavity surface-emitting lasers (VCSELs). In the paper, kinetics of AlAs steam oxidation process in cylindrically symmetric VCSEL mesa structures is investigated theoretically. Compact analytical formulae describing the oxidation process are derived and discussed. The process parameters are extracted from existing experimental data. The parameters are found to be strongly dependent on the AlAs layer thickness and temperature. It is shown that significant differences exist between the predictions of the cylindrical model and those of widely used one-dimensional Cartesian model. Our detailed model can therefore be very important for achieving a good control of the oxidation process in fabrication of modern VCSELs
8
Content available remote High-performance 980-nm strained-layer InGaAs/GaAs quantum-well lasers
Bugajski M., Regiński K., Mroziewicz B., Kubica J.M., Sajewicz P., Piwoński T., Zbroszczyk M.
Optica Applicata
|
2001
|
Vol. 31, nr 2
267-271
EN
Reports fabrication of strained-layer InGaAs/GaAs separate-confinement-heterostructure single-quantum-well (SCH SQW) lasers operating in the wavelength range of 980 nm. Design process of the devices involved simulation of their above-threshold operation including all relevant physical phenomena. The lasers were characterized at room temperature in the pulsed operation regime at frequency v=5 kHz and pulse length tau =200 ns. Threshold current densities of the order J/sub th/=280 A/cm/sup 2/ and differential efficiency eta =0.40 W/A were obtained for devices with cavities of 700 mu m in length and broad contacts of 100 mu m in width
9
Content available remote Design considerations for GaAs/(AlGa)As SCH and GRIN-SCH quantum-well laser structures. II. The results
Czyszanowski T., Wasiak M., Nakwaski W.
Optica Applicata
|
2001
|
Vol. 31, nr 2
325-336
EN
A detailed optical model of complex multi-layered structures of the separate-confinement-heterostructure (SCH) lasers as well as graded-index (GRIN) SCH lasers presented in the first part of the paper is used to discuss some of the possible modifications of their structure to reduce room-temperature thresholds. Recommended design parameters have been found for each structure. Surprisingly, performance of relatively simple SCH lasers is found to be at least comparable with that of much more complex GRIN-SCH lasers.
10
Content available remote Design considerations for GaAs/(AlGa)As SCH and GRIN-SCH quantum-well laser structures. I. The model
Czyszanowski T., Wasiak M., Nakwaski W.
Optica Applicata
|
2001
|
Vol. 31, nr 2
313-323
EN
Some design modifications and optimization of the GaAs/(AlGa)As separate-confinement-heterostructure (SCH) as well as graded-index separate-confinement-heterostructure (GRIN-SCH) semiconductor lasers to reduce their room-temperature (RT) thresholds are discussed. To this end, a detailed optical model of arsenide diode lasers is developed and used to compare the impact of some structure details on RT lasing thresholds. In the model presented in the first part of the paper, both optical gain and losses are modeled rigorously. Optical fields within complex multi-layered structures of the SCH lasers are found using the downhill method. Threshold carrier concentrations are determined from the general balance of radiation gain and losses. As a result of the simulation, recommended basic design parameters for the above structures are deduced in the second part of the paper.
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